In order to estimate the mean 30-year fixed mortgage rate for a home loan in the United States, a random sample of 26 recent loans is taken. The average calculated from this sample is 7.20%. It can be assumed that 30-year fixed mortgage rates are normally distributed with a standard deviation of 0.7%. Compute 95% and 99% confidence intervals for the population mean 30-year fixed mortgage rate.

Answers

Answer 1

Answer:

The 95% CI is (6.93% , 7.47%)

The 99% CI is (6.85% , 7.55%)

Step-by-step explanation:

We have to estimate two confidence intervals (95% and 99%) for the population mean 30-year fixed mortgage rate.

We know that the population standard deviation is 0.7%.

The sample mean is 7.2%. The sample size is n=26.

The z-score for a 95% CI is z=1.96 and for a 99% CI is z=2.58.

The margin of error for a 95% CI is

[tex]E=z\cdot \sigma/\sqrt{n}=1.96*0.7/\sqrt{26}=1.372/5.099=0.27[/tex]

Then, the upper and lower bounds are:

[tex]LL=\bar x-z\cdot\sigma/\sqrt{n}=7.2-0.27=6.93\\\\ UL=\bar x+z\cdot\sigma/\sqrt{n} =7.2+0.27=7.47[/tex]

Then, the 95% CI is

[tex]6.93\leq x\leq 7.47[/tex]

The margin of error for a 99% CI is

[tex]E=z\cdot \sigma/\sqrt{n}=2.58*0.7/\sqrt{26}=1.806/5.099=0.35[/tex]

Then, the upper and lower bounds are:

[tex]LL=\bar x-z\cdot\sigma/\sqrt{n}=7.2-0.35=6.85\\\\ UL=\bar x+z\cdot\sigma/\sqrt{n} =7.2+0.35=7.55[/tex]

Then, the 99% CI is

[tex]6.85\leq x\leq 7.55[/tex]


Related Questions

A 1980 study was conducted whose purpose was to compare the indoor air quality in offices where smoking was permitted with that in offices where smoking was not permitted. Measurements were made of carbon monoxide (CO) at 1:20 p.m. in 40 work areas where smoking was permitted and in 40 work areas where smoking was not permitted. Where smoking was permitted, the mean CO level was 11.6 parts per million (ppm) and the standard deviation CO was 7.3 ppm. Where smoking was not permitted, the mean CO was 6.9 ppm and the standard deviation CO was 2.7 ppm.

To test for whether or not the mean CO is significantly different in the two types of working environments, perform a t-test for unequal variance and report the p-value

Answers

Answer:

The null hypothesis is not rejected.

There is no enough evidence to support the claim that the CO level is lower  in non-smoking working areas compared to smoking work areas.

P-value = 0.07.

Step-by-step explanation:

We have to perform a test on the difference of means.

The claim that we want to test is that CO is less present in no-smoking work areas.

Then, the null and alternative hypothesis are:

[tex]H_0: \mu_1-\mu_2=0\\\\H_a:\mu_1-\mu_2 > 0[/tex]

being μ1: mean CO level in smoking work areas, and μ2: mean CO level in no-smoking work areas.

The significance level is assumed to be 0.05.

Smoking areas sample

Sample size n1=40.

Sample mean M1=11.6

Sample standard deviation s1=7.3

No-smoking areas sample

Sample size n2=40

Sample mean M2=6.9

Sample standard deviation s2=2.7

First, we calculate the difference between means:

[tex]M_d=M_1-M_2=11.6-7.3=4.3[/tex]

Second, we calculate the standard error for the difference between means:

[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{7.3^2}{40}+\dfrac{2.7^2}{40}}=\sqrt{\dfrac{53.29+7.29}{40}}=\sqrt{\dfrac{60.58}{40}}\\\\\\s_{M_d}=\sqrt{1.5145}=1.23[/tex]

Now, we can calculate the t-statistic:

[tex]t=\dfrac{M_d-(\mu_1-\mu_2)}{s_{M_d}}=\dfrac{4.3-0}{1.23}=3.5[/tex]

The degrees of freedom are calculated with the Welch–Satterthwaite equation:

[tex]df=\dfrac{(\dfrac{s_1^2}{n_1}+\dfrac{s_2^2}{n_2})^2}{\dfrac{s_1^4}{n_1(n_1-1)}+\dfrac{s_2^4}{n_2(n_2-1)}} \\\\\\\\df=\dfrac{(\dfrac{7.3^2}{40}+\dfrac{2.7^2}{40})^2}{\dfrac{7.3^4}{40(39)}+\dfrac{2.7^4}{40(39)}} =\dfrac{(\dfrac{53.29}{40}+\dfrac{7.29}{40})^2}{\dfrac{2839.82}{1560}+\dfrac{53.14}{1560}} \\\\\\\\df=\dfrac{1.5145^2}{1.8545}=\dfrac{2.2937}{1.8545}=1.237[/tex]

The P-value for this right tail test, with 1.237 degrees of freedom and t=3.5 is:

[tex]P-value=P(t>3.5)=0.07[/tex]

The P-value is bigger than the significance level, so the effect is not significant. The null hypothesis is not rejected.

There is no enough evidence to support the claim that the CO level is lower  in non-smoking working areas compared to smoking work areas.

Final answer:

The p-value, which indicates the likelihood that the difference in CO levels in the work areas is due to chance, can be computed from the mean CO levels and the standard deviations using a t-test for unequal variance. The computation requires several steps, including calculating the degrees of freedom and the t-statistic.

Explanation:

To conduct the t-test for unequal variance, we need to follow several steps. Below are the necessary steps:

Compute the degrees of freedom: df = (s1^2/n1 + s2^2/n2)^2 / { [ (s1^2/n1)^2 / (n1-1) ]  + [ (s2^2/n2)^2 / (n2-1) ] } where s1 and s2 are the standard deviations, n1 and n2 are the sample sizes. Compute the t-statistic: t = (x1 - x2) / sqrt (s1^2/n1 + s2^2/n2) where x1 and x2 are the sample means. Finally, use a t-distribution table or an online calculator to find the p-value based on the t-statistic and the degrees of freedom

 

In this scenario, the mean CO levels and standard deviations in work areas where smoking was permitted and not permitted are given. By plugging these into the formulas, we can find the t-value and then use the t-distribution to find the corresponding p-value.

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The plane x+y+2z=8 intersects the paraboloid z=x2+y2 in an ellipse. Find the points on this ellipse that are nearest to and farthest from the origin. Point farthest away occurs at ( , , ). Point nearest occurs at (

Answers

Answer:

The minimum distance of   √((195-19√33)/8)  occurs at  ((-1+√33)/4; (-1+√33)/4; (17-√33)/4)  and the maximum distance of  √((195+19√33)/8)  occurs at (-(1+√33)/4; - (1+√33)/4; (17+√33)/4)

Step-by-step explanation:

Here, the two constraints are

g (x, y, z) = x + y + 2z − 8  

and  

h (x, y, z) = x ² + y² − z.

Any critical  point that we find during the Lagrange multiplier process will satisfy both of these constraints, so we  actually don’t need to find an explicit equation for the ellipse that is their intersection.

Suppose that (x, y, z) is any point that satisfies both of the constraints (and hence is on the ellipse.)

Then the distance from (x, y, z) to the origin is given by

√((x − 0)² + (y − 0)² + (z − 0)² ).

This expression (and its partial derivatives) would be cumbersome to work with, so we will find the the extrema  of the square of the distance. Thus, our objective function is

f(x, y, z) = x ² + y ² + z ²

and

∇f = (2x, 2y, 2z )

λ∇g = (λ, λ, 2λ)

µ∇h = (2µx, 2µy, −µ)

Thus the system we need to solve for (x, y, z) is

                           2x = λ + 2µx                         (1)

                           2y = λ + 2µy                       (2)

                           2z = 2λ − µ                          (3)

                           x + y + 2z = 8                      (4)

                           x ² + y ² − z = 0                     (5)

Subtracting (2) from (1) and factoring gives

                     2 (x − y) = 2µ (x − y)

so µ = 1  whenever x ≠ y. Substituting µ = 1 into (1) gives us λ = 0 and substituting µ = 1 and λ = 0  into (3) gives us  2z = −1  and thus z = − 1 /2 . Subtituting z = − 1 /2  into (4) and (5) gives us

                            x + y − 9 = 0

                         x ² + y ² +  1 /2  = 0

however, x ² + y ² +  1 /2  = 0  has no solution. Thus we must have x = y.

Since we now know x = y, (4) and (5) become

2x + 2z = 8

2x  ² − z = 0

so

z = 4 − x

z = 2x²

Combining these together gives us  2x²  = 4 − x , so

2x²  + x − 4 = 0 which has solutions

x =  (-1+√33)/4

and

x = -(1+√33)/4.

Further substitution yeilds the critical points  

((-1+√33)/4; (-1+√33)/4; (17-√33)/4)   and

(-(1+√33)/4; - (1+√33)/4; (17+√33)/4).

Substituting these into our  objective function gives us

f((-1+√33)/4; (-1+√33)/4; (17-√33)/4) = (195-19√33)/8

f(-(1+√33)/4; - (1+√33)/4; (17+√33)/4) = (195+19√33)/8

Thus minimum distance of   √((195-19√33)/8)  occurs at  ((-1+√33)/4; (-1+√33)/4; (17-√33)/4)  and the maximum distance of  √((195+19√33)/8)  occurs at (-(1+√33)/4; - (1+√33)/4; (17+√33)/4)

In this question, we have 2 constraints:

The plane                        g ( x , y , z ) = x + y + 2 z - 8

The paraboloid             h ( x , y , z ) = x² + y² - z

We need to apply Lagrange Multipliers to answer it

The solution are:

The nearest point P = ( -9.06/4   ,   -9.06 /4  ,  6.23 )

The farthest point Q  (  (7.06) /4  ,  (7.06) /4 ,  10.26)

The Objective Function (F) is the distance between the ellipse and the origin, In this case,  we don´t need to know the equation of the ellipse

The Objective Function is

F = √ x² + y² + z²    and as this function has the same critical points that

F  = x² + y² + z²  we will use this one

Then:

     δF/δx  = 2×x               δF/δy  = 2×y                 δF/δz = 2×z

   λ ×δg/δx =  λ                  λ δg/δy = λ                  λ δg/δz = 2× λ    

   μ× δh/δx = 2× μ×x         μ× δh/δy = 2× μ×y        μ× δh/δz= - μ

Therefore we get our five equations.

2×x  =  λ   +  2× μ×x      (1)

2×y  =  λ   +  2× μ×y      (2)

2×z  = 2× λ  -  μ             (3)

x + y + 2 z - 8 = 0          (4)

x² + y² - z = 0                (5)

Subtracting equation (2) from equation (1)

2×x  - 2×y  = 2× μ×x -  2× μ×y

( x - y ) =  μ × ( x - y )       then   μ = 1   and by substitution in eq. (2)

2×y  =  λ   +  2×y        then       λ  = 0

From eq. (3)

2×z  = - 1                                   z = -1/2

By subtitution in eq. (4) and (5)

x  +  y  - 1 - 8 = 0     ⇒   x  +  y  = 9

x² + y² + 1/2  = 0        this equation has no solution.

If we make  x = y

Equation (4) and (5) become

2× x + 2× z = 8

2×x² - z = 0        ⇒         z = 2×x²

2× x + 4×x² = 8     ⇒   2×x² + x - 8 = 0

Solving for x          x₁,₂ = ( -1 ± √ 1 + 64 ) / 4

x₁,₂ = ( -1 ± √65 ) 4

x₁ = (-1 + √65) /4            x₂ = ( -1 - √65) /4          √ 65  = 8.06

x₁ = 1.765            x₂ = - 2.265

And  z = 2×x²      ⇒      z₁ =  6.23          z₂  =

And critical points are:

P ( x₁  y₁  z₁ )      (  (7.06) /4  ,  (7.06) /4 ,  6.23 )

Q ( x₂  y₂ z₂ )      ( -9.06/4   ,   -9.06 /4  ,  10.26 )

And by simple  inspeccion we see That

minimum distance is the point P = ( -9.06/4   ,   -9.06 /4  ,  6.23 )

the point Q  (  (7.06) /4  ,  (7.06) /4 ,  10.26) is the farthest point

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Given f(x) = x² - 10x + 22, what is the range of f?

Answers

Answer:

[-3, ∞)

Step-by-step explanation:

There are many ways to find the range but I will use the method I find the easiest.

First, find the derivative of the function.

f(x) = x² - 10x + 22

f'(x) = 2x - 10

Once you find the derivative, set the derivative equal to 0.

2x - 10 = 0

Solve for x.

2x = 10

x = 5

Great, you have the x value but we need the y value. To find it, plug the x value of 5 back into the original equation.

f(x) = x² - 10x + 22

f(5) = 5² - 10(5) + 22

      = 25 - 50 +22

      = -3

Since the function is that of a parabola, the value of x is the vertex and the y values continue going up to ∞.

This means the range is : [-3, ∞)

Another easy way is just graphing the function and then looking at the range. (I attached a graph of the function below).

Hope this helped!

Answer:

The correct answer is B

Step-by-step explanation:

Find the slope of the line that passes through each pair of points

What is the slope of -2,1 and 1,-2

Answers

Answer:

-1

Step-by-step explanation:

The slope of the line can be found by

m = (y2-y1)/(x2-x1)

    = (-2-1)/(1--2)

     =-3 /(1+2)

      =-3/3

       -1

Which graph represents the solution set of the inequality Negative 14.5 less-than x?
A. A number line going from negative 15 to negative 11. An open circle is at negative 13.5. Everything to the right of the circle is shaded.

B. A number line going from negative 15 to negative 11. A closed circle is at negative 14. Everything to the right of the circle is shaded.

C. A number line going from negative 15 to negative 11. An open circle is at negative 14.5. Everything to the right of the circle is shaded.

D. A number line going from negative 15 to negative 11. A closed circle is at negative 15. Everything to the right of the circle is shaded.

Answers

The solution of the inequality -14.5 < x represents graph which is correct option C

What is inequality?

Inequality is the defined as mathematical statements that have a minimum of two terms containing variables or numbers is not equal.

-14.5 < x

x > -14.5

A number line going from negative 15 to negative 11. An open circle is at negative 14.5. Everything to the right of the circle is shaded.

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Find product (7m+8)(4m +1)

Answers

Step-by-step explanation:

[tex](7m + 8)(4m + 1) \\ = 7m(4m + 1) + 8(4m + 1) \\ = 28 {m}^{2} + 7m + 32m + 8 \\ \purple { \bold{= 28 {m}^{2} + 39m + 8}}[/tex]

A radioactive substance decays at a rate proportional to the amount (mass) that is present. Denote the proportionality constant by the letter r. Suppose we start with 1 kg of the substance. (a) (1pt) Write the differential equation and initial condition for the mass m(t) of the substance as a function of time t (measured in hours). (b) (1pt) Find the solution as a function of t and r. (c) (1pt) Suppose that, one hour later, 0.8 kgs remain. Find The constant r. (d) (1pt) Suppose we measure time in minutes. Find the differential equation for m(s), if s denotes time in minutes.

Answers

Answer:

a) The differential equation is:  [tex]\frac{dm}{dt} =r\,m[/tex]

with initial condition: [tex]m(0)=1\,\,kg[/tex]

b) m(t) =\,1\,\,kg\,\,e^{r\,t}

c)  r=-0.22314

d) Same differential equation, but the solution function would have a different value for "r" resultant from dividing by 60:[tex]\frac{ln(0.8)}{60} =r\\r=-0.003719[/tex]

Step-by-step explanation:

Part a)

The differential equation is:  [tex]\frac{dm}{dt} =r\,m[/tex]

with initial condition: [tex]m(0)=1\,\,kg[/tex]

Part b)

The solution for a function whose derivative is a multiple of the function itself, must be associated with exponential of base "e":

[tex]m(t) =\,A\,e^{r\,t}[/tex]   with [tex]A = m(0) = 1\,\,kg[/tex]

So we can write the function as: [tex]m(t) =\,1\,\,kg\,\,e^{r\,t}[/tex]

Part c)

To find the constant "r", we use the information given on the amount of substance left after one hour (0.8 kg) by using t = 1 hour, and solving for "r" in the equation:

[tex]m(t) =\,1\,\,kg\,\,e^{r\,t}\\m(1) =\,1\,\,kg\,\,e^{r\,(1)}\\0.8\,\,kg=\,1\,\,kg\,\,e^{r\,(1)}\\0.8=e^{r\,(1)}\\ln(0.8)=r\\r=-0.22314[/tex]

where we have rounded the answer to the 5th decimal place. Notice that this constant "r" is negative, associated with a typical exponential decay.

Part d)

The differential equation if we measure the time in minutes would be the same, but its solution would have a different constant "r" given by the answer to the amount of substance left after 60 minutes have elapsed:

[tex]m(t) =\,1\,\,kg\,\,e^{r\,t}\\m(1) =\,1\,\,kg\,\,e^{r\,(60)}\\0.8\,\,kg=\,1\,\,kg\,\,e^{r\,(60)}\\0.8=e^{r\,(60)}\\\frac{ln(0.8)}{60} =r\\r=-0.003719[/tex]

What is the Pythagorean Therom

Answers

a^2 + b^2 = c^2

Where c^2 is the hypotenuse

Answer:

its a fundamental relation in Euclidean geometry among the three sides of a right triangle. It states that the area of the square whose side is the hypotenuse is equal to the sum of the areas of the squares on the other two sides.

Formula:

[tex]a^{2} + b^{2} = c^{2}[/tex]

A ski resort gets an average of 2,000 customers per weekday with a standard deviation of 800 customers. Assume the underlying distribution is normal. Use an appropriate normal transformation to calculate the probability a ski resort averages more than 3,000 customers per weekday over the course of four weekdays.

Answers

Answer:

0.62% probability that a ski resort averages more than 3,000 customers per weekday over the course of four weekdays

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem, we have that:

[tex]\mu = 2000, \sigma = 800, n = 4, s = \frac{800}{\sqrt{4}} = 400[/tex]

Trobability a ski resort averages more than 3,000 customers per weekday over the course of four weekdays.

This is 1 subtracted by the pvalue of Z when X = 3000. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

By the Central Limit Theorem

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{3000 - 2000}{400}[/tex]

[tex]Z = 2.5[/tex]

[tex]Z = 2.5[/tex] has a pvalue of 0.9938

1 - 0.9938 = 0.0062

0.62% probability that a ski resort averages more than 3,000 customers per weekday over the course of four weekdays

A recent study examined hearing loss data for 1981 U.S. teenagers. In this sample, 369 were found to have some level of hearing loss. News of this study spread quickly, with many news articles blaming the prevalence of hearing loss on the higher use of ear buds by teens. At MSNBC (8/17/2010), Carla Johnson summarized the study with the headline: "1 in 5 U.S. teens has hearing loss, study says." To investigate whether this is an appropriate or a misleading headline, you will conduct a test of significance with the following hypotheses: Null: π = 0.20 Alternative: π ≠ 0.20

Answers

Answer:

There is no enough evidence to support the claim that the proportion of US teens that have some level of hearing loss differs from 20%.

P-value=0.12

Step-by-step explanation:

We have to perform a test of hypothesis on the proportion.

The claim is that the proportion of US teens that have some level of hearing loss differs from 20%.

Then, the null and alternative hypothesis are:

[tex]H_0: \pi=0.20\\\\H_a:\pi\neq0.20[/tex]

The significance level is assumed to be 0.05.

The sample, of size n=1981, has 369 positive cases. Then, the proportion is:

[tex]p=X/n=369/1981=0.186[/tex]

The standard error of the proportion is:

[tex]\sigma_p=\sqrt{\dfrac{\pi(1-\pi)}{n}}=\sqrt{\dfrac{0.2*0.8}{1981}}=\sqrt{ 0.000081 }= 0.009[/tex]

Now, we can calculate the statistic z:

[tex]z=\dfrac{p-\pi+0.5/n}{\sigma_p}=\dfrac{0.186-0.20+0.5/1981}{0.009}=\dfrac{-0.014}{0.009}=-1.556[/tex]

The P-value for this two-tailed test is:

[tex]P-value=2*P(z<-1.556)=0.12[/tex]

The P-value is below the significance level, so the effect is not significant. The null hypothesis failed to be rejected.

There is no enough evidence to support the claim that the proportion of US teens that have some level of hearing loss differs from 20%.

Since -0.700 falls within this range (-1.96 to 1.96), you fail to reject the null hypothesis (H0). This means that there is not enough evidence to conclude that the true proportion of U.S. teens with hearing loss is different from 0.20.

To investigate whether the headline "1 in 5 U.S. teens has hearing loss, study says" is appropriate or misleading, you can conduct a hypothesis test based on the given hypotheses:

Null Hypothesis (H0): π = 0.20 (The true proportion of U.S. teens with hearing loss is 0.20, or 20%.)

Alternative Hypothesis (H1): π ≠ 0.20 (The true proportion of U.S. teens with hearing loss is not equal to 0.20.)

Here, π represents the population proportion of U.S. teenagers with hearing loss.

To test these hypotheses, you can perform a hypothesis test for a population proportion using a significance level (alpha), such as 0.05 (5%). You can use the z-test for proportions to determine whether the observed proportion of hearing loss in the sample significantly differs from the claimed proportion of 0.20.

The test statistic for the z-test for proportions is calculated as:

z= (p−π)/√(π(1−π)/n)

​Where:

p is the sample proportion (369 out of 1981 in this case).

π is the hypothesized population proportion (0.20).

n is the sample size (1981).

Calculate the sample proportion:

p= 369/1981​ ≈0.186

Now, calculate the test statistic

z= (0.186−0.20)/√(0.20(1−0.20)/1981)

​Calculate the standard

SE=√(0.20(1−0.20)/1981)≈0.020

Now, calculate

z≈ (0.186−0.20)/0.020​ ≈−0.700

Now, you can find the critical values for a two-tailed test at a 95% confidence level (alpha = 0.05). You can use a standard normal distribution table or calculator to find the critical z-values. For a two-tailed test with alpha = 0.05, the critical z-values are approximately -1.96 and 1.96.

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An object with a mass
of 300 kg is observed to
| accelerate at the rate
Tof 4 m/s2. Calculate the
i total force required.

Answers

Step-by-step explanation:

[tex]F=ma\\\\F=(300kg)(4m/s^2)\\F=1200N[/tex]

Bill Connors, a quality control manager at a Menlo Park Electronics Company, knows his company has been making surge protectors with a 10% rate of defective units. Bill decides to test 20 randomly selected surge protectors to see how many are defective. Let X represent the mumber f defective unit nth . Asminnpndenc answer the folowing :a) What type of probability distribution does X have (include the value(s) of any parameters)? b) What is the probability that more than one surge protector is defective? c) What is the probability that the number of defective surge protectors is between three and five? d) How many surge protectors would you expect to be defective? e) Find the standard deviation X.

Answers

Answer:

a) Binomial distribution, with n=20 and p=0.10.

b) P(x>1) = 0.6082

c) P(3≤X≤5) = 0.3118

d) E(X) = 2

e) σ=1.34

Step-by-step explanation:

a) As we have a constant "defective" rate for each unit, and we take a random sample of fixed size, the appropiate distribution to model this variable X is the binomial distribution.

The parameters of the binomial distribution for X are n=20 and p=0.10.

[tex]X\sim B(0.10,20)[/tex]

b) The probability of k defective surge protectors is calculated as:

[tex]P(x=k) = \binom{n}{k} p^{k}q^{n-k}[/tex]

In this case, we want to know the probability that more than one unit is defective: P(x>1). This can be calculated as:

[tex]P(x>1)=1-(P(0)+P(1))\\\\\\P(x=0) = \binom{20}{0} p^{0}q^{20}=1*1*0.1216=0.1216\\\\P(x=1) = \binom{20}{1} p^{1}q^{19}=20*0.1*0.1351=0.2702\\\\\\ P(x>1)=1-(0.1216+0.2702)=1-0.3918=0.6082[/tex]

c) We have to calculate the probability that the number of defective surge protectors is between three and five: P(3≤X≤5).

[tex]P(3\leq X\leq 5)=P(3)+P(4)+P(5)\\\\\\P(x=3) = \binom{20}{3} p^{3}q^{17}=1140*0.001*0.1668=0.1901\\\\P(x=4) = \binom{20}{4} p^{4}q^{16}=4845*0.0001*0.1853=0.0898\\\\P(x=5) = \binom{20}{5} p^{5}q^{15}=15504*0*0.2059=0.0319\\\\\\P(3\leq X\leq 5)=P(3)+P(4)+P(5)=0.1901+0.0898+0.0319=0.3118[/tex]

d) The expected number of defective surge protectors can be calculated from the mean of the binomial distribution:

[tex]E(X)=\mu_B=np=20*0.10=2[/tex]

e) The standard deviation of this binomial distribution is:

[tex]\sigma=\sqrt{np(1-p)}=\sqrt{20*0.1*0.9}=\sqrt{1.8}=1.34[/tex]

What’s the first step to solve the equation x-6=14

Answers

You change six to a negative then add it to 14 which is Which is eight then divide 8 by 1 and the answers eight
Final answer:

To solve the equation x - 6 = 14, the first step is to isolate the variable 'x'. You do this by adding 6 to both sides of the equation, which results in x = 14 + 6. Therefore, 'x' equals 20.

Explanation:

The subject of this question is Mathematics, and it is focusing on solving a basic algebraic equation: x - 6 = 14. When you are asked to solve an equation, you're figuring out what numbers you can replace the variable with to make the equation true. In this case, the variable is 'x', and your goal is to find what number 'x' stands for. The first step to solve the equation is to isolate 'x'. This means you want 'x' to stand alone on one side of the equation. To accomplish this, you need to perform the same operation on both sides of the equation to maintain equality. Here, you would add 6 to both sides of the equation (opposite of subtracting 6), which simplifies to: x = 14 + 6. So, 'x' equals 20.

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6x + 3y - 9 when x = 6, y = 9

Answers

Answer:

54

Step-by-step explanation:

6(6)+3(9)-9

=54

Answer:

54

Step-by-step explanation:

First, since it's given the x and y values, you need to plug them in.

6(6) + 3(9) - 9

36 + 27 - 9

63 - 9

54

write an equation for the amount of money, m that will be collected if b boxes of chocolate are sold.

Answers

Answer:

m = b(t)

t= the price per box

Answer:

m = ?b

Step-by-step explanation:

m = total

b = number of boxes sold

? = price of chocolate

a circle with the radius of 1 cm sits inside a 11cm by 12cm rectangle.What is the area of the shaded region?

Answers

Answer:

128.86 square cm

Step-by-step explanation:

Area of shaded region = Area of rectangle - Area of circle

[tex] = 11 \times 12 - \pi {r}^{2} \\ = 132 - 3.14 \times {1}^{2} \\ = 132 - 3.14 \\ = 128.86 \: {cm}^{2} \\ [/tex]

Answer:

128.86

Step-by-step explanation:

4x - 2y =7
X + 2y =3
What are x and y ??

Answers

4x - 2y = 7

x + 2y =  3

5x = 10

x=2 and y=0

Answer:

{x,y} = {2,1/2}

Step-by-step explanation:

Solve by Substitution :

1. Solve equation [2] for the variable  x  

 [2]    x = -2y + 3

2. Plug this in for variable  x  in equation [1]

  [1]    4•(-2y+3) - 2y = 7

  [1]     - 10y = -5

3.Solve equation [1] for the variable  y  

  [1]    10y = 5

  [1]    y = 1/2

By now we know this much :

   x = -2y+3

   y = 1/2

4.Use the  y  value to solve for  x  

   x = -2(1/2)+3 = 2

Solution :

{x,y} = {2,1/2}

A particle moves according to a law of motion s = f(t), 0 ≤ t ≤ 6, where t is measured in seconds and s in feet. f(t) = cos(πt/3) (a) Find the velocity at time t (in ft/s). v(t) = (b) What is the velocity after 2 s? (Round your answer to two decimal places.) v(2) = ft/s

Answers

Answer:

[tex](a)v(t)=-\frac{\pi }{3}sin(\frac{\pi t}{3})[/tex]

(b)-0.91 ft/s

Step-by-step explanation:

Given the position function  s = f(t) where f(t) = cos(πt/3), 0 ≤ t ≤ 6

(a)The velocity at time t in ft/s is the derivative of the position vector.

[tex]If\: f(t)=cos(\frac{\pi t}{3})\\f'(t)=-\frac{\pi }{3}sin(\frac{\pi t}{3})\\v(t)=-\frac{\pi }{3}sin(\frac{\pi t}{3})[/tex]

(b)Velocity after 2 seconds

When t=2

[tex]v(2)=-\frac{\pi }{3}sin(\frac{\pi *2}{3})\\=-0.91 ft/s[/tex]

The particle moves 0.91 ft/s in the opposite direction.

Final answer:

The velocity v(t) of a particle moving with function s=f(t)=cos(πt/3) is given by v(t) = -(π/3)sin(πt/3). When t=2 seconds, the velocity of the particle is approximately -1.81 ft/s.

Explanation:

To find the velocity, v(t), at time t for the particle you need to find the derivative of s = f(t) = cos(πt/3) with respect to time, t. Using the chain rule, the derivative will be v(t) = -sin(πt/3) * (π/3), which simplifies to v(t) = -(π/3)sin(πt/3). This formula will provide the velocity of the particle at any time, t, within the given range.

To find the velocity of the particle after 2 seconds, substitute t = 2 into the velocity function. So, v(2) = -(π/3)sin(π*2/3). This simplifies to approximately -1.81 ft/s, when rounded to two decimal places. Therefore, the velocity of the particle at 2 seconds is -1.81 ft/s.

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If ST≅SV and m∠SUT=68°, what is m∠TUV?

Answers

Answer:

136

Step-by-step explanation:

Take 68 x 2 since the side lengths are equal.

Final answer:

Given the properties of isosceles triangle, where congruent sides have equal opposite angles, and that the given angle ∠SUT = 68°, it implies that ∠TUV also equals 68°.

Explanation:

The question involves the principles of geometry, specifically the properties of angles and congruent lines. Given that ST≅SV and m∠SUT = 68°, it means that these two line segments are equal in length and that the angle of SUT is 68 degrees.

Since ST and SV are congruent in an isosceles triangle, the angles opposite these sides are equal. Hence, the measure of ∠SUT and ∠TUV are equal. We know m∠SUT = 68°, so therefore, m∠TUV = 68°.

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Find f such that f'(x) = 5x² + 9x - 7 and f(0) = 8.

Answers

Answer:

[tex]\frac{5}{3}x^3+\frac{9}{2}x^2-7x+8\\[/tex]

Step-by-step explanation:

Integrate your function with respect to x to get the non-differentiated form.

[tex]\int(5x^2+9x-7)dx=\frac{5}{3}x^3+\frac{9}{2}x^2-7x+c\\[/tex]

Plug in your known value of x to get your value for your constant

[tex]f(0) = 8\\ \frac{5}{3}(0^3)+\frac{9}{2}(0^2)-7(0)+c = 8 \\c=8[/tex]

This gives you your function to be

[tex]\frac{5}{3}x^3+\frac{9}{2}x^2-7x+8\\[/tex]

Final answer:

To find f such that f'(x) = 5x² + 9x - 7 and f(0) = 8, integrate the given function and solve for the constant of integration using the given condition. The resulting equation is f(x) = (5/3)x³ + (9/2)x² - 7x + 8.

Explanation:

To find f such that f'(x) = 5x² + 9x - 7 and f(0) = 8, we need to integrate f'(x) to find the equation for f(x). Let's find the antiderivative of 5x² + 9x - 7, which is  (5/3)x³ + (9/2)x² - 7x + C. To determine the value of C, we can use the given condition f(0) = 8. Substituting x = 0 into the equation, we get 8 = (5/3)(0)³ + (9/2)(0)² - 7(0) + C. Solving for C, we find that C = 8. Therefore, the equation for f(x) is f(x) = (5/3)x³ + (9/2)x² - 7x + 8.

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Lola is using a one-sample t-t- test for a population mean, µμ , to test the null hypothesis, H0:µ=40 mg/dLH0:μ=40 mg/dL , against the alternative hypothesis, H1:µ>40 mg/dLH1:μ>40 mg/dL . Her results are based on a simple random sample of size n=15 . The value of the one-sample t-t- statistic is t=1.457 .

If Lola requires her results to be statistically significant at significance level of a 0.10, what can she conclude and why?

a. Because the exact p-value is unknown, she cannot make a conclusion.
b. She should not reject the null hypothesis because p > 0.10.
c. She should not reject the null hypothesis because p< 0.10.
d. She should reject the null hypothesis because p< 0.10,
e. She should not reject the null hypothesis because 0.10< p < 0.05.

Answers

Answer:

d. She should reject the null hypothesis because p < 0.10.

Step-by-step explanation:

We have a t statistic, so let's solve for the P-value on our calculators. (tcdf on a TI-84 calculator is 2nd->VARS->6.)

tcdf(left bound, right bound, degrees of freedom)

Our left bound is t=1.457. Our right bound is infinity, because we're interested in the hypothesis µ>40 mg/dL. We use 999 to represent infinity in the calculator.Our degrees of freedom is n-1 = 15-1 = 14.

tcdf(1.457,999,14) = .084

.084 < P-value of .10, so we reject the null hypothesis.

Lola's conclusion should be "She should reject the null hypothesis because p< 0.10". Option D is correct.

Given information:

Lola is using a one-sample t-test for a population mean, µ, to test the null hypothesis.

[tex]\mu=40[/tex]

Sample random size is, [tex]n=15[/tex].

The value of the one-sample t-statistic is [tex]t=1.457[/tex].

The left bound will be [tex]t=1.457[/tex] and the value of [tex]n-1[/tex] will be 15-1=14.

Now, use the calculator to find the value of p. The found value of p will be,

[tex]p=0.084[/tex]

So, the value of p is less than 0.1.

Therefore, Lola's conclusion should be "She should reject the null hypothesis because p< 0.10". Option D is correct.

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| 3. Find the Area of the triangle.
8.6 yd
10.9 yd

Answers

Given:

The base of the triangle = 8.6 yd

The height of the triangle = 10.9 yd

To find the area of the triangle.

Formula

The area of a triangle with b as base and h as height is

[tex]A=\frac{1}{2}bh[/tex]

Now,

Taking, b= 8.6 and h = 10.9 we get,

[tex]A=\frac{1}{2}(8.6)(10.9)[/tex] sq yd

or, [tex]A= 46.87[/tex] sq yd

Hence,

The area of the given triangle is 46.87 sq yd.

Answer:

46.87 yd^2

Step-by-step explanation:

The area of the triangle is given by

A = 1/2 bh

A = 1/2 (8.6)(10.9)

A =46.87 yd^2

What is the final transformation in the composition of transformations that maps pre-image GHJK to image G’H”J”K”?

Answers

Answer:

B on edge 2020

Step-by-step explanation:

Applying [tex]\[M_f = M_n \cdot M_{n-1} \cdot ... \cdot M_3 \cdot M_2 \cdot M_1\][/tex] final transformation matrix to the pre-image GHJK [tex](\(P\))[/tex], we get the image G'H''J''K''.

To determine the final transformation that maps the pre-image GHJK to the image G'H''J''K'', we need to break down the transformations and apply them in the correct order.

Let's assume there are several transformations involved, such as translations, rotations, reflections, or dilations. Each transformation can be represented by a matrix or a set of rules.

Let's denote the initial pre-image GHJK as [tex]\(P\).[/tex] The series of transformations can be represented as [tex]\(T_1 \cdot T_2 \cdot T_3 \cdot ... \cdot T_n\)[/tex], where [tex]\(T_1\) to \(T_n\)[/tex] are individual transformations.

To find the final transformation, we need to multiply the matrices representing these transformations in the reverse order. If [tex]\(M_1, M_2, M_3, ..., M_n\)[/tex] are the matrices representing [tex]\(T_1, T_2, T_3, ..., T_n\)[/tex]respectively, the final transformation matrix [tex]\(M_f\)[/tex] would be:

[tex]\[M_f = M_n \cdot M_{n-1} \cdot ... \cdot M_3 \cdot M_2 \cdot M_1\][/tex]

Applying this final transformation matrix to the pre-image GHJK [tex](\(P\))[/tex], we get the image G'H''J''K''.

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The radius of a circle is 9 miles. What is the length of a 180° arc?

Answers

Final answer:

The length of a 180° arc in a circle with a radius of 9 miles is 9π miles, which is half of the circle's total circumference.

Explanation:

The radius of a circle is the distance from the center to any point on the circle, and the arc length is the distance measured along the circumference of the circle that corresponds to a particular angle. In our case, to calculate the length of a 180° arc, we first need the circumference of the circle, which can be found using the formula 2πr (where r is the radius), and then we find the proportion of the circumference that corresponds to a 180° angle, or half a circle.

The circumference of a circle with a radius of 9 miles is given by:
Circumference = 2π × 9 miles = 18π miles.
Since 180° is half of a full 360° rotation, the arc length for 180° will be half of the circumference:
Arc Length for 180° = ½ × 18π miles = 9π miles.

CAN SOMEONE HELP ME PLEASEEEplease and thank u

Answers

Answer:

C,H,I..............

A Rhombus with diagonal 1 equal to 5 ft and diagonal 2 equal to 8 ft

Answers

Answer:

Area = 20 ft²

Step-by-step explanation:

Area of a thrombus

½ × d1 × d2

½ × 5 × 8

20

Answer:

20 ft squared

Step-by-step explanation:

The area of a rhombus can be calculated by multiplying its diagonals by each other and then halving that product: A = [tex]\frac{1}{2} d_1d_2[/tex]

Here, we know that [tex]d_1[/tex] = 5 and [tex]d_2[/tex] = 8. So, we have the equation: A = [tex]\frac{1}{2} *5*8=(1/2)*40=20[/tex]

Thus, the area is 20 ft squared.

Hope this helps!

In one common system for finding a grade-point average, or GPA:

A=4, B=3, C=2, D=1, F=0

The GPA is calculated by multiplying the number of credit hours for a course and the number assigned to each grade, and then adding these products. Then divide the sum by the total number of credit hours. Because each course grade is weighted according to the number of credits of the course, GPA is also called a weighted mean. Calculate the GPA for this transcript:

Sociology: 3cr: A, Biology: 4cr: C, Music 1cr: B, Math 4cr:B, English 3cr: C

Answers

Answer:

The GPA for this transcript is:

GPA = 2.73

Step-by-step explanation:

A=4, B=3, C=2, D=1, F=0

Sociology: 3cr: A, Biology: 4cr: C, Music 1cr: B, Math 4cr:B, English 3cr: C

Total number of credit hour = 3 + 4 + 1 + 4 + 3 = 15

Product for each course = the number of credit hours for a course * the number assigned to each grade

Sociology = 3 * 4 = 12

Biology = 4 * 2 = 8

Music = 1 * 3 = 3

Math = 4 * 3 = 12

English = 3 * 2 = 6

Total product = 12 + 8 + 3 + 12 + 6 = 41

GPA = Sum of product / Total credit hour

GPA = 41 / 15 = 2.7333333

GPA = 2.73

Answer:

The results is 2.73.

Step-by-step explanation:

First let's make the calculations for each course;

For Sociology, an A (which is 4) for 3 credits equals to 12.

For Biology, a C (which is 2) for 4 credits equals to 8.

For Music, a B (which is 3) for 1 credit equals to 3.

For Math, a B (which is 3) for 4 credits equals to 12.

For English, a C (which is 2) for 3 credits equals to 6.

If we sum them all up, we find the results to be 41 and the total credits to be 15 for the 5 courses.

Lastly we should divide 41/15 which will be equal to 2.73 which is the GPA.

I hope this answer helps.

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.8. (Round your answers to four decimal places.)
(a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 17 pins is at least 51?
answer is 0.011

(b) What is the (approximate) probability that the sample mean hardness for a random sample of 45 pins is at least 51?

Answers

Answer:

a) 0.011 = 1.1% probability that the sample mean hardness for a random sample of 17 pins is at least 51

b) 0.0001 = 0.1% probability that the sample mean hardness for a random sample of 45 pins is at least 51

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem, we have that:

[tex]\mu = 50, \sigma = 1.8[/tex]

(a) If the distribution is normal, what is the probability that the sample mean hardness for a random sample of 17 pins is at least 51?

Here [tex]n = 17, s = \frac{1.8}{\sqrt{17}} = 0.4366[/tex]

This probability is 1 subtracted by the pvalue of Z when X = 51. So

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

By the Central Limit Theorem

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{51 - 50}{0.4366}[/tex]

[tex]Z = 2.29[/tex]

[tex]Z = 2.29[/tex] has a pvalue of 0.9890

1 - 0.989 = 0.011

0.011 = 1.1% probability that the sample mean hardness for a random sample of 17 pins is at least 51

(b) What is the (approximate) probability that the sample mean hardness for a random sample of 45 pins is at least 51?

Here [tex]n = 17, s = \frac{1.8}{\sqrt{45}} = 0.2683[/tex]

[tex]Z = \frac{X - \mu}{s}[/tex]

[tex]Z = \frac{51 - 50}{0.0.2683}[/tex]

[tex]Z = 3.73[/tex]

[tex]Z = 3.73[/tex] has a pvalue of 0.9999

1 - 0.9999 = 0.0001

0.0001 = 0.1% probability that the sample mean hardness for a random sample of 45 pins is at least 51

Final answer:

To find the probability that the sample mean hardness for a random sample of 17 pins is at least 51, we can convert it to a standard normal distribution and use the z-score formula. The probability is approximately 0.011. For a sample size of 45 pins, the probability is approximately 0.001.

Explanation:

To find the probability that the sample mean hardness for a random sample of 17 pins is at least 51, we can convert it to a standard normal distribution and use the z-score formula. The formula for the z-score is:

z = (x - μ) / (σ / sqrt(n))

where x is the value we are interested in (51), μ is the mean (50), σ is the standard deviation (1.8), and n is the sample size (17).

Plugging in the values, we get:

z = (51 - 50) / (1.8 / sqrt(17))

Calculating this, we find that the z-score is approximately 1.044. Looking up this z-score in the z-table, we find that the probability is 0.853. However, we are interested in the probability that the hardness is at least 51, which means we need to find the area to the right of the z-score. So, we subtract the probability from 1:

Probability = 1 - 0.853 = 0.147, or approximately 0.011 when rounded to four decimal places.

Therefore, the probability that the sample mean hardness for a random sample of 17 pins is at least 51 is approximately 0.011.

To find the probability that the sample mean hardness for a random sample of 45 pins is at least 51, we follow the same process. The only difference is that the sample size is now 45 instead of 17. Plugging in the values into the z-score formula, we find that the z-score is approximately 3.106. Looking up this z-score in the z-table, we find that the probability is 0.999. Subtracting this probability from 1, we get:

Probability = 1 - 0.999 = 0.001.

Therefore, the probability that the sample mean hardness for a random sample of 45 pins is at least 51 is approximately 0.001.

19. EL CONDENADO A MUERTE. En los tiempos de la antigüedad la gracia o el castigo se dejaban frecuentemente al azar. Así, éste es el caso de un reo al que un sultán decidió que se salvase o muriese sacando al azar una papeleta de entre dos posibles: una con la sentencia "muerte", la otra con la palabra "vida", indicando gracia. Lo malo es que el Gran Visir, que deseaba que el acusado muriese, hizo que en las dos papeletas se escribiese la palabra "muerte". ¿Cómo se las arregló el reo, enterado de la trama del Gran Visir, para estar seguro de salvarse? Al reo no le estaba permitido hablar y descubrir así el enredo del Visir.

Answers

Answer:

English plz

Step-by -step explanation:

what dose this say

Final answer:

El condenado sobrevivió al destruir una de las 'papeletas de muerte' sin leerla, y utilizar la ley del Sultán a su favor para afirmar que su 'papeleta de muerte' destruida era la 'papeleta de vida'.

Explanation:

El reo aseguró su supervivencia actuando de manera astuta. Sabiendo que ambas papeletas tenían la palabra muerte, decidió escoger una y, sin leerla, la destruyó por completo. Entonces solicitó que se leyera la papeleta restante, si en la papeleta restante dice muerte, entonces es obvio que la papeleta que destruyó debía tener la sentencia de vida, ya que según el Sultán, el Gran Visir hizo dos papeletas diferentes. De esta manera, aunque el Gran Visir deseaba que obtuviera la sentencia de muerte, el reo se salvó por su astucia sin necesidad de revelar el complot del Visir.

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A chemist examines 15 sedimentary samples for nitrate concentration. The mean nitrate concentration for the sample data is 0.670 cc/cubic meter with a standard deviation of 0.0616.

a. Determine the 80% confidence interval for the population mean nitrate concentration. Assume the population is approximately normal. Round your answer to three decimal places.
b. Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

Answers

Answer:

(a) The 80% confidence interval for the population mean nitrate concentration is (0.648, 0.692).

(b) The critical value of t that should be used in constructing the 80% confidence interval is 1.345.

Step-by-step explanation:

Let X = nitrate concentration.

The sample mean nitrate concentration is, [tex]\bar x=0.670[/tex] cc/cubic meter.

The sample standard deviation of the nitrate concentration is, [tex]s=0.0616[/tex].

It assumed that the population is approximately normal.

And since the population standard deviation is not known, we will use a t-interval.

The (1 - α)% confidence interval for population mean (μ) is:

[tex]CI=\bar x\pm t_{\alpha/2, (n-1)}\times \frac{s}{\sqrt{n}}[/tex]

(a)

The critical value of t for α = 0.20 and degrees of freedom, (n - 1) = 14 is:

[tex]t_{\alpha/2, (n-1)}=t_{0.20/2, (15-1)}=t_{0.10, 14}=1.345[/tex]

*Use a t-table for the critical value.

Compute the 80% confidence interval for the population mean nitrate concentration as follows:

[tex]CI=\bar x\pm t_{\alpha/2, (n-1)}\times \frac{s}{\sqrt{n}}[/tex]

     [tex]=0.670\pm 1.345\times \frac{0.0616}{\sqrt{15}}[/tex]

     [tex]=0.670\pm 0.022\\=(0.648, 0.692)\\[/tex]

Thus, the 80% confidence interval for the population mean nitrate concentration is (0.648, 0.692).

(b)

The critical value of t for confidence level (1 - α)% and (n - 1) degrees of freedom is:

[tex]t_{\alpha/2, (n-1)}[/tex]

The value of  is:

α = 0.20

And the degrees of freedom is,

(n - 1) = 15 - 1 = 14

Compute the critical value of t for confidence level 80% and 14 degrees of freedom as follows:

[tex]t_{\alpha/2, (n-1)}=t_{0.20/2, (15-1)}[/tex]

               [tex]=t_{0.10, 14}\\=1.345[/tex]

*Use a t-table for the critical value.

Thus, the critical value of t that should be used in constructing the 80% confidence interval is 1.345.

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