A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 732 hours. A random sample of 28 light bulbs has a mean life of 704 hours. Assume the population is normally distributed and the population standard deviation is 65 hours. At alphaequals0.05​, do you have enough evidence to reject the​ manufacturer's claim?

Answers

Answer 1

Answer:

[tex]z=\frac{704-732}{\frac{65}{\sqrt{28}}}=-2.279[/tex]      

[tex]p_v =P(z<-2.279)=0.0113[/tex]  

If we compare the p value and the significance level given for example [tex]\alpha=0.05[/tex] we see that [tex]p_v<\alpha[/tex] so we can conclude that we can reject the null hypothesis, and the the true mean is significantly lower than 732 hours so we have enough evidence to reject the claim

Step-by-step explanation:

Data given and notation      

[tex]\bar X=704[/tex] represent the sample mean

[tex]\sigma=65[/tex] represent the standard deviation for the population      

[tex]n=28[/tex] sample size      

[tex]\mu_o =732[/tex] represent the value that we want to test    

[tex]\alpha[/tex] represent the significance level for the hypothesis test.    

t would represent the statistic (variable of interest)      

[tex]p_v[/tex] represent the p value for the test (variable of interest)  

State the null and alternative hypotheses.      

We need to conduct a hypothesis in order to determine if the true mean is at least 732 or no, the system of hypothesis would be:      

Null hypothesis:[tex]\mu \geq 732[/tex]      

Alternative hypothesis:[tex]\mu < 732[/tex]      

We know the population deviation, so for this case is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:      

[tex]z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}[/tex] (1)      

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".  

Calculate the statistic      

We can replace in formula (1) the info given like this:      

[tex]z=\frac{704-732}{\frac{65}{\sqrt{28}}}=-2.279[/tex]      

Calculate the P-value      

Since is a one-side lower test the p value would be:      

[tex]p_v =P(z<-2.279)=0.0113[/tex]  

Conclusion      

If we compare the p value and the significance level given for example [tex]\alpha=0.05[/tex] we see that [tex]p_v<\alpha[/tex] so we can conclude that we can reject the null hypothesis, and the the true mean is significantly lower than 732 hours so we have enough evidence to reject the claim

Answer 2

Answer:

Step-by-step explanation:

We would set up the hypothesis test. This is a test of a single population mean since we are dealing with mean

For the null hypothesis,

µ ≥ 732

For the alternative hypothesis,

µ < 732

Since the population standard deviation is given, z score would be determined from the normal distribution table. The formula is

z = (x - µ)/(σ/√n)

Where

x = lifetime of the bulb

µ = mean lifetime

σ = standard deviation

n = number of samples

From the information given,

µ = 732

x = 704 hours

σ = 65 hours

n = 28

z = (704 - 732)/(65/√28) = - 2.28

Looking at the normal distribution table, the probability corresponding to the z score is 0.011

Since alpha, 0.05 > than the p value, 0.011, then we would reject the null hypothesis. Therefore, At a 5% level of significance, there is enough evidence to reject the​ manufacturer's claim


Related Questions

For a school fundraiser, Ayana needs to sell 40 rolls of wrapping paper. So far, she has sold 7 rolls to her grandmother, 2 rolls to her uncle, and 9 rolls to a neighbor. How many more rolls of wrapping paper does Ayana need to sell?

Answers

Answer:

22?

Step-by-step explanation:

Just take 40 and subtract the 7 to get 33 and then 2 to get 31 and 9 to get 22.

Answer:

22 more rolls

Step-by-step explanation:

if she needs to sell 40 and she has sold 9+7+2=18 than you subtract 18 from 40 getting 22 more rolls

The cross section of a water bin is shaped like a trapezoid. The bases of the trapezoid are 28 feet and 6 feet long. It has an area of 34 square feet. What is the height of the cross section?

Answers

Answer:

The height of the cross section if 2 feet

Step-by-step explanation:

To solve this problem recall the formula for the area of a trapezoid of bases B (larger base) and b (smaller base) and height H:

[tex]Area = \frac{(B+b)\,H}{2}[/tex]

Therefore, for our case we have:

[tex]Area = \frac{(B+b)\,H}{2}\\34 \,ft^2 = \frac{(28\,ft+6\,ft)\,H}{2}\\34 \,ft^2 = \frac{(34 \,ft)\,H}{2}[/tex]

So, now we can solve for the height H:

[tex]34 \,ft^2 = \frac{(34 \,ft)\,H}{2}\\2\,*\,34 \,ft^2 =34\,ft\,* H\\H=\frac{2\,*\,34 \,ft^2}{34\,ft}\\ H=2\,ft[/tex]

One of the largest cookies on record had a diameter of 78.75 feet. What is the approximate circumference of the cookie? Use 3.14 for n. Round to tenths place.

Answers

Answer:

247.3 Ft

Step-by-step explanation:

c=3.14(78.75)

c=247.245 *rounded*

Final answer:

The question was about calculating the circumference of a circle using its diameter. The diameter was given, and the formula for circumference 'C = πd' was used, where 'd' was 78.75 feet and 'π' was approximated at 3.14. The circumference comes out to be approximately 247.35 feet when rounded to the nearest tenth.

Explanation:

The subject in this question is the measurement of the circumference of a cookie given its diameter, a basic concept in geometry in the field of Mathematics. Circumference which is the distance around a circle can be calculated using the formula 'C = πd', where 'C' is the circumference, 'd' is the diameter and 'π' is a constant approximately equal to 3.14.

In this case, the diameter 'd' of the cookie is 78.75 feet. So, by substituting the values into the formula, we get: C = 3.14 * 78.75.

After performing this calculation, you'll find that the approximate circumference of the cookie is 247.35 feet when rounded to the nearest tenth.

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Graham sold 6 magazines less than double what Adrianne sold, a. Which of the following expressions represents Graham's sales?

6a − 2
2(a − 6)
a^2 − 6
2a − 6

Answers

The correct answer will be the last option 2a-6
the answer is the second one

Sarah is fighting a sinus infection her doctor prescribed a nasal spray and I know a biotic to fight the infection the active ingredient in milligrams remaining in the bloodstream from the nasal spray in, tea, and the anabiotic a comity, our models in the functions below where tea is the time in hours and some medications were taken

Answers

Answer:

a) The antibiotic is made with a greater initial amount of active ingredient

b) The two medications will have the same amount of active ingredients in the blood stream at exactly 8 hours after first taking the medication.

Step-by-step explanation

Active ingredient of Nasal spray left in the bloodstream is modelled as

n(t) = ((t + 1)/(t + 5)) + (18/(t² + 8t + 15))

Active ingredient of Antibiotic left in the bloodstream is modelled as

a(t) = 9/(t+3)

with t in hours.

a) At the instance of usage, the active ingredient for both drugs are at their initial concentration as they appear in the drugs.

So, we find the amount of active ingredient for each drug in the bloodstream at t=0 and compare.

For nasal spray,

n(t) = ((t + 1)/(t + 5)) + (18/(t² + 8t + 15))

At t = 0

n(0) = (1/5) + (18/15) = 1.4

For antibiotics,

a(t) = 9/(t+3)

At t=0

a(0) = (9/3) = 3

3 > 1.4

Hence, the antibiotic is made with a greater initial amount of active ingredient.

b) when both medications will have the same amount of active ingredients in the bloodstream, n(t) = a(t)

n(t) = ((t + 1)/(t + 5)) + (18/(t² + 8t + 15))

a(t) = 9/(t+3)

Note that (t² + 8t + 15) = (t + 3)(t + 5)

When n(t) = a(t)

((t + 1)/(t + 5)) + (18/(t² + 8t + 15)) = 9/(t+3)

Multiplying through by (t² + 8t + 15) or more properly written as (t + 3)(t + 5)

(t+1)(t+3) + 18 = 9(t+5)

t² + 4t + 3 + 18 = 9t + 45

t² - 5t - 24 = 0

Solving the quadratic equation

t = 8 or t = -3

Time can't be negative, hence, t = 8 hours.

Hope this Helps!!!

How are the archetypes presented in these two passages
different?
The first passage shows Antigone as a warrior, and the
second passage shows Boadicea as a tragic heroine.
The first passage shows Antigone as a tragic heroine,
and the second passage shows Boadicea as a sage.
The first passage shows Antigone as a rebel, and the
second passage shows Boadicea as a warrior.
The first passage shows Antigone as a villain, and the
second passage shows Boadicea as a sage.

Answers

Answer: the third answer. Explanation below.

Step-by-step explanation:

The first passage shows Antigone as a rebel because she chooses to defy the State. The second passage shows Boadicea as a warrior because she "herself led the soldiers, encouraging them with her brave words."

Final answer:

Antigone and Boadicea are presented with different archetypal roles across the passages; Antigone as a warrior, tragic heroine, rebel, and villain; and Boadicea as a tragic heroine, sage, warrior, and sage again.

Explanation:

The archetypes presented in these passages are different in the roles and characteristics assigned to Antigone and Boadicea. In the first set of passages, Antigone is depicted as a warrior, then as a tragic heroine, next as a rebel, and lastly as a villain. Conversely, Boadicea is presented as a tragic heroine, followed by a sage, then as a warrior, and finally as a sage once again. These variations represent unique depictions of these mythical figures, giving us different lenses to interpret their actions and significance within their respective narratives.

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4. 4csc^2x+3cscx-1=0

Answers

Answer: 8cxs^c= -3 csc (x) +1

Step-by-step explanation:

To solve for c you need to simplify both sides of the equation, then isolating the variable

Answer:

x = - π/2   or x = - π/2 + 2nπ       n = integer

Step-by-step explanation:

4csc²x+3cscx-1=0

(csc x + 1) (4csc x - 1) = 0

csc x = - 1 or csc x = 1/4

1/ sin x = - 1      or 1 / sin x = 1/4

sin x = - 1      or sin x = 4  (x no solution when sin x = 4)

sin x = - 1

x = - π/2   or x = - π/2 + 2nπ       n = integer

What is the solution to this system of equations?

x − 2y = 15
2x + 4y = -18

Answers

Answer:

The answer to your question is     (3, -6)

Step-by-step explanation:

Data

           x  -  2y  =  15                  Equation l

         2x +  4y  = -18                  Equation ll

Solve the system of equations by elimination

-Multiply equation l by 2

         2x  -  4y  =  30

         2x  + 4y  = -18

         4x   + 0    = 12

                    4x = 12

                      x = 12/4

                      x = 3

-Substitute x in equation l

          3  -  2y = 15

-Solve for y

               -2y = 15 - 3

               - 2y = 12

                   y = 12/-2

                   y = -6

-Solution

              (3, -6)

Answer:

C.  x = 3, y = -6

Step-by-step explanation

Answer is correct from Plato

I need to k ow number four

Answers

Answer:

Step-by-step explanation:

How many solution(s) are there
for this system?
6y=12x+36
15y=45x60

Answers

Final answer:

The given system of equations has one unique solution because the lines represented by the equations have different slopes, hence they intersect at exactly one point.

Explanation:

To answer how many solutions there are for the given system of equations:

6y=12x+36
15y=45x+60 (Assuming the '+60' was meant instead of '60', as '+60' makes it a linear equation)

We first simplify both equations to determine if they are identical, parallel, or intersecting.

For the first equation, we divide by 6:

y = 2x + 6

For the second equation, assuming a typo and it should be '+60', we divide by 15:

y = 3x + 4

Since the slopes (2 and 3) are different, the lines are not parallel and will intersect at exactly one point. Therefore, there is one unique solution to this system.

The video store is having a sale on movie videos. They normally sell for $24.99, but are on sale for $12.99. Mr. Berger purchased 3 videos on sale. How much did he save?​

Answers

$24.99 x3 =74.97
$12.99 x3 =38.97
$74.97-$38.97 =$36.00 Saved

PLEASE HELP!!! AND EXPLAIN IF YOU CAN !!!
sin(-295°) = _____. sin 65° sin 295° sin 25° -sin 65°

Answers

Answer:

Step-by-step explanation:

sin(-295°)=-sin (295)=-sin (360-65)=-(-sin 65°)=sin (65°)

Fill in the numbers that go into the blank boxes. The numbers have to multiply to be the top number and add to be the bottom number.

Answers

Answer: 6 and 6

Step-by-step explanation:6x6=36

6+6=12

The fish population of a lake is decreasing each year. A study is conducted. But, unfortunately some data was lost. The researcher found in her notes that in year one the fish population was 18000 fish and in year three the fish population was 8000 fish. Assume a constant rate of decay. Find a formula F

Answers

Answer:

[tex]F(t) = 18000(0.6666)^{t}[/tex]

Step-by-step explanation:

The fish population after t years can be modeled by the following equation:

[tex]F(t) = F(0)(1-r)^{t}[/tex]

In which F(0) is the initial population and r is the constant rate of decay.

Year one the fish population was 18000

This means that [tex]F(0) = 18000[/tex]

In year three the fish population was 8000 fish.

Two years later, so [tex]F(2) = 8000[/tex]

[tex]F(t) = F(0)(1-r)^{t}[/tex]

[tex]8000 = 18000(1-r)^{2}[/tex]

[tex](1-r)^{2} = 0.4444[/tex]

[tex]\sqrt{(1-r)^{2}} = \sqrt{0.4444}[/tex]

[tex]1 - r = 0.6666[/tex]

[tex]r = 0.3334[/tex]

So

[tex]F(t) = 18000(0.6666)^{t}[/tex]

Find the length of the radius in a circle if the diameter is 10 feet

Answers

The radius is 5 feet because if you want to find the radius, you have to divide the diameter by two.


In a right triangle, the value of cos B = 3/5. What is the value of sin B?
[Leave your answer as a fraction]

Answers

Answer:

4/5

Step-by-step explanation:

cos B = 3/5

cos Ф = adjacent/hypothesis

hypothesis ² = adjacent² + opposite²

5²= 3²+ o²

25 = 9+o²

25-9=o²

16 = o²

√16 = o = 4

Sin B = opposite/hypothesis = 4/5

Which expressions are equivalent to the one below click all that apply 21x/3x

Answers

After simplifying [tex]\(\frac{{21^x}}{{7^x}}\)[/tex], we find it equivalent to [tex]\(3^x\)[/tex], confirming options a, b, and f as correct.

To simplify the expression [tex]\(\frac{{21^x}}{{7^x}}\)[/tex], we can use the property of exponents which states that [tex]\(a^m/a^n = a^{m-n}\)[/tex]. Applying this property, we get:

[tex]\[\frac{{21^x}}{{7^x}} = \frac{{(7 \cdot 3)^x}}{{7^x}} = \frac{{7^x \cdot 3^x}}{{7^x}} = 3^x\][/tex]

So, the simplified expression is [tex]\(3^x\).[/tex]

Now, let's check each option:

a. [tex]\(\frac{{7^x \cdot 3^x}}{{7^x}} = 3^x\)[/tex]. This expression is equivalent to the simplified form.

b. [tex]\((\frac{{21}}{{7}})^x = 3^x\)[/tex]. This expression is equivalent to the simplified form.

c. [tex]\(3\)[/tex]. This expression is not equivalent to the simplified form.

d. [tex]\((21 - 7)^x = 14^x\)[/tex]. This expression is not equivalent to the simplified form.

e. [tex]\(3^{x-7}\)[/tex]. This expression is not equivalent to the simplified form.

f. [tex]\(3^x\)[/tex]. This expression is equivalent to the simplified form.

Therefore, the expressions equivalent to [tex]\(\frac{{21^x}}{{7^x}}\)[/tex] are options a, b, and f.

The question probable maybe:

Given in the attachment

Please help!!!!!!!!!!!!!!!

Answers

Answer:

150

Step-by-step explanation:

1 box is 5 x 5 which=25 x 6 boxes=150

150 squared is your answer

Answer: 150

Step-by-step explanation:

The side of one cube is 5. 5 * 5 = 25 So 25 is the surface area of one cube side. A cube a 6 sides, and 25 * 6 = 150. Therefore, 150 is the surface area of the cube.

A small accounting firm has 444 accountants who each earn a different salary between \$50{,}000$50,000dollar sign, 50, comma, 000 and \$60{,}000$60,000dollar sign, 60, comma, 000, and a 5^{\text{th}}5 th 5, start superscript, start text, t, h, end text, end superscript accountant who works part-time for tax season and earns \$10{,}000$10,000dollar sign, 10, comma, 000. [Show data] 1010 5252 5454 5656 5858 The firm decides to get rid of the part-time accountant and keep the other 444 salaries the same. How will getting rid of the part-time accountant affect the mean and median? Choose 1 answer: Choose 1 answer: (Choice A) A Both the mean and median will increase, but the median will increase by more than the mean. (Choice B) B Both the mean and median will increase, but the mean will increase by more than the median. (Choice C) C The mean will increase, and the median will decrease. (Choice D) D The median will increase, and the mean will decrease.

Answers

Answer:

The correct option is;

(Choice B) Both the mean and median will increase, but the mean will increase by more than the median.

Step-by-step explanation:

Here, we are expected to show the differences (advantages/properties) of the mean and median

Note that the definition of the mean is the sum of the value of all data points divided by the number of data points

Assuming the four accountants each earn $ 55,000.00

Therefore, initial mean before getting rd of the part-time accountant is

(55+ 55+ 55 + 55 + 10)/5 = 46

Final mean after the part-time accountant is gone =(55+ 55+ 55 + 55 )/4 = 55

Therefore the mean increases

However, the median is given by the middle value when the list of values are arranged in increasing order as

55, 55, 55, 55, 10

Therefore the initial median is 55

Final median after the part-time accountant is gone is

55, 55, 55, 55

Therefore, final = (55 + 55)/2 = 55

That is the median remains the same that is little or increase.

Therefore, since the range of values for the full time accountants salaries weigh less than the difference between the average full time salary and a single part time, both the mean and the median will increase but the mean will increase more than the median

Answer:

b

Step-by-step explanation:

determine whether the vectors u and v are parallel, orthogonal, or neither. u=(9,0), v=(0,-9)

Answers

Answer:

orthogonal

Step-by-step explanation:

If the dot product of the two vectors is 0, then they must be orthogonal.

[tex]u*v=9(0)-9(0) = 0[/tex]

Answer: c

Step-by-step explanation: edge 2021

What is closest to the difference between the means of the two dot plots?

Answers

Answer: The answer is B. 1.0

Step-by-step explanation:

That’s the closest mean

Answer:

A is 15.27 and B is 12.05

Step-by-step explanation:

Simplify the expression 2(-9+9v)

Answers

2(-9) = -18
2(9v) = 18v

-18+18v

Find the volume of the composite solid. Round your answer to the nearest tenth.

Answers

Answer: I think it's 50.2 but I might be wrong

A right triangle whose hypotenuse is 3 centimeters long is revolved about one of its legs to generate a right circular cone. Find the radius, height, and volume of the right cone that will have the greatest volume when constructed this way.

Answers

Answer:

The height of the right circular cone when constructed this way is [tex]\sqrt3[/tex] cm.

The radius of the right circular cone when constructed this way is [tex]\sqrt6[/tex] cm.

The volume of the right circular cone when constructed this way is [tex]6\sqrt3 \pi[/tex] cm³.

Step-by-step explanation:

Given that,

A right triangle whose hypotenuse is 3 cm long is revolved .

Then other two legs of the triangle will be radius and height of the cone.

Assume the height and radius of the cone be h and r respectively.

From Pythagorean Theorem :

h²+r²=3²

⇒ r²= 9 - h²

Then the volume of the cone is

V= π r²h

⇒ V= π(9-h²)h                [ ∵ r²= 9 - h²]

⇒V= π(9h - h³)

Differentiating with respect to h

V'=π(9 - 3h²)

Again differentiating with respect to h

V''= π(-6h)

⇒V''= (-6πh)

To maximum or minimum ,we set V'=0

π(9 - 3h²)=0

⇒3h²=9

⇒h²=3

[tex]\Rightarrow h=\sqrt3[/tex]

Now, [tex]V''|_{h=\sqrt3}=-6\pi (\sqrt3)<0[/tex].

Since at [tex]h=\sqrt3[/tex],V''<0.

The volume of cone is maximum at [tex]h=\sqrt3[/tex] cm when constructed this way.

The height of the right circular cone when constructed this way is [tex]\sqrt3[/tex] cm.

The radius of the right circular cone when constructed this way  [tex]r=\sqrt{9-(\sqrt3)^2[/tex]

   =  [tex]\sqrt{9-3}[/tex]

   [tex]=\sqrt6[/tex] cm.

The volume of the  right circular cone when constructed this way is

=π r²h

[tex]=\pi (\sqrt6)^2\sqrt3[/tex]

[tex]=6\sqrt3 \pi[/tex] cm³

What is the least common denominator for:

3/x and 2/4xy

Answers

Answer:

the least common denominator is 4xy

!3 3/4 as an inproper fraction

Answers

Answer:

55/4

Step-by-step explanation:

13 3/4

(13×4 + 3)/4

55/4

Answer:

hope this helps!

Suppose you select a ball by first picking one of two boxes at random and then selecting a ball from this box. The first box contains two white balls and three blue balls and the second box contains four white balls and one blue ball. What is the probability that you picked a ball from the first box if you have drawn a blue ball

Answers

Answer:

Probability of selecting a ball from the first ball if it is a blue ball =  = 0.75

Step-by-step explanation:

Number of blue balls in the first box = 3

Number of blue balls in the second box = 1

Total number of blue balls = 3 + 1

Total number of blue balls = 4

Probability = (Number of possible outcomes)/(Number of total outcomes)

Probability of selecting a ball from the first ball if it is a blue ball = 3/4

Probability of selecting a ball from the first ball if it is a blue ball =  = 0.75

The ​half-life of a radioactive element is 130​ days, but your sample will not be useful to you after​ 80% of the radioactive nuclei originally present have disintegrated. About how many days can you use the​ sample? Round to the nearest day.

Answers

Answer:

We can use the sample about 42 days.

Step-by-step explanation:

Decay Equation:

[tex]\frac{dN}{dt}\propto -N[/tex]

[tex]\Rightarrow \frac{dN}{dt} =-\lambda N[/tex]

[tex]\Rightarrow \frac{dN}{N} =-\lambda dt[/tex]

Integrating both sides

[tex]\int \frac{dN}{N} =\int\lambda dt[/tex]

[tex]\Rightarrow ln|N|=-\lambda t+c[/tex]

When t=0, N=[tex]N_0[/tex] = initial amount

[tex]\Rightarrow ln|N_0|=-\lambda .0+c[/tex]

[tex]\Rightarrow c= ln|N_0|[/tex]

[tex]\therefore ln|N|=-\lambda t+ln|N_0|[/tex]

[tex]\Rightarrow ln|N|-ln|N_0|=-\lambda t[/tex]

[tex]\Rightarrow ln|\frac{N}{N_0}|=-\lambda t[/tex].......(1)

                            [tex]\frac{N}{N_0}=e^{-\lambda t}[/tex].........(2)

Logarithm:

[tex]ln|\frac mn|= ln|m|-ln|n|[/tex] [tex]ln|ab|=ln|a|+ln|b|[/tex][tex]ln|e^a|=a[/tex] [tex]ln|a|=b \Rightarrow a=e^b[/tex] [tex]ln|1|=0[/tex]

130 days is the half-life of the given radioactive element.

For half life,

[tex]N=\frac12 N_0[/tex],  [tex]t=t_\frac12=130[/tex] days.

we plug all values in equation (1)

[tex]ln|\frac{\frac12N_0}{N_0}|=-\lambda \times 130[/tex]

[tex]\rightarrow ln|\frac{\frac12}{1}|=-\lambda \times 130[/tex]

[tex]\rightarrow ln|1|-ln|2|-ln|1|=-\lambda \times 130[/tex]

[tex]\rightarrow -ln|2|=-\lambda \times 130[/tex]

[tex]\rightarrow \lambda= \frac{-ln|2|}{-130}[/tex]

[tex]\rightarrow \lambda= \frac{ln|2|}{130}[/tex]

We need to find the time when the sample remains 80% of its original.

[tex]N=\frac{80}{100}N_0[/tex]

[tex]\therefore ln|{\frac{\frac {80}{100}N_0}{N_0}|=-\frac{ln2}{130}t[/tex]

[tex]\Rightarrow ln|{{\frac {80}{100}|=-\frac{ln2}{130}t[/tex]

[tex]\Rightarrow ln|{{ {80}|-ln|{100}|=-\frac{ln2}{130}t[/tex]

[tex]\Rightarrow t=\frac{ln|80|-ln|100|}{-\frac{ln|2|}{130}}[/tex]

[tex]\Rightarrow t=\frac{(ln|80|-ln|100|)\times 130}{-{ln|2|}}[/tex]

[tex]\Rightarrow t\approx 42[/tex]

We can use the sample about 42 days.

Final answer:

The radioactive sample can be used for approximately 390 days.

Explanation:

The half-life of a radioactive element is the time it takes for half of the radioactive nuclei to decay. In this case, the half-life is 130 days. The sample is considered no longer useful when 80% of the nuclei have decayed. To determine how many days the sample can be used, we need to find the number of half-lives it takes for 80% of the nuclei to decay.

80% is the same as 0.8, which means 20% (or 0.2) of the nuclei remain. Each half-life reduces the amount of nuclei by half, so we can set up an equation:

0.2 = (1/2)^n

where n is the number of half-lives.

To solve for n, we can take the logarithm of both sides:

n = log_base(1/2)(0.2)

Using a calculator, we find n ≈ 2.737.

Since we can't have a fraction of a half-life, we round up to the nearest whole number, which gives us n = 3.

Now, we can find the number of days by multiplying the half-life by the number of half-lives:

Number of days = 130 days * 3 = 390 days.

Therefore, the sample can be used for approximately 390 days.

A green die and a red die are tossed. What is the probability that a "4" shows on the green die and a "5" shows on the red die?

Answers

Answer:

1 out of 6 for green die and 1 out of 6 for red die

Step-by-step explanation:

As we know there are six numbers on both of the dices

so if we toss a die there is a 1 out of 6 outcomes that a 4 comes out for the green die and 1 out of 6 outcomes again for the red die

The probability that a 4 shows on the green die and a 5 shows on the red die is given by P ( C ) = 1/36

What is Probability?

The probability that an event will occur is measured by the ratio of favorable examples to the total number of situations possible

Probability = number of desirable outcomes / total number of possible outcomes

The value of probability lies between 0 and 1

Given data ,

Let the probability that a 4 shows on the green die and a 5 shows on the red die be represented as P ( C )

Now , the number of outcomes in a roll of die = { 1 , 2 , 3 , 4 , 5 , 6 } = 6 outcomes

And , probability that a 4 shows on the green die P ( A ) = 1/6

The probability that a 5 shows on a red die P ( B ) = 1/6

Now , it is an independent experiment

So , the compound probability is P ( C ) = P ( A ) . P ( B )

And , the probability that a 4 shows on the green die and a 5 shows on the red die P ( C ) = ( 1/6 ) ( 1/6 )

The probability that a 4 shows on the green die and a 5 shows on the red die P ( C ) = 1/36

Hence , the probability is P ( C ) = 1/36

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A high-speed bullet train accelerates and decelerates at the rate of 4 ft/s 2 . Its maximum cruising speed is 90 mi/h . (Round your answers to three decimal places.) (a) What is the maximum distance the train can travel if it accelerates from rest until it reaches its cruising speed and then runs at that speed for 15 minutes

Answers

Answer:

22.9 miles

Step-by-step explanation:

We are given that

Acceleration=Deceleration=a=[tex]4ft/s^2[/tex]

Maximum cruising speed,v=[tex]90mi/h=90\times \frac{5280}{3600}=132ft/s[/tex]

1 hour=3600 s

1 mile=5280 feet

Time,t=15 minutes=[tex]15\times 60=900 s[/tex]

1 min=60 s

Initial speed,u=0

[tex]v=u+at[/tex]

Substitute the values

[tex]132=0+4t[/tex]

[tex]t=\frac{132}{4}=33 s[/tex]

[tex]s=u+\frac{1}{2}at^2=0+\frac{1}{2}(4)(33)^2=2178 ft[/tex]

Distance,d=[tex]speed\times time=vt=132\times 900=118800ft[/tex]

Total distance=s+d=2178+118800=120978ft

Total distance=[tex]\frac{120978}{5280}=22.9miles[/tex]

Hence, the maximum distance traveled by train =22.9 miles

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