Mathematics College

Devon wants to know if drinking milk before bed helps teenagers sleep. he chooses 10 friends on his high school basketball team for his study. every night for one month the friends drink a glass of milk before bed and later record how many hours they sleep that night. Describe three reasons why Devon's study design is flawed.

Answers

Answer 1
Three reasons why this design is flawed are that he is only surveying the basketball players. The population sample should include a mix of many teenagers if this is the hypothesis. The second reason this is flawed is that he is only collection data of ten people (whom are his friends), causing possible biased data and not enough evidence with only 10 people. Another flaw is the cup size. How much is each person drinking? Cups come on different sizes, but the amount should be the same for all.
Answer 2

Answer:

The three reasons Devon's study is flawed because:

1. The sample size is very small. You cannot conclude anything based on small samples.

2. Sample is biased as Devon chose basket ball players and such players have proper sleep pattern and waking up pattern as compared to normal people. So, the study cannot be generalized.

3. Devon must have studied their sleep pattern before experimenting also, so that some quantitative data on change is available for conclusion.

Related Questions

A table is going to be painted. How much less surface area of the table will be painted if the underside remains unpainted. The length is 22 in, the width is 20 in, and the height is 1 in

Answers

The answer is the surface area will be 440 square inches less.

hey can you please help me posted picture of question

Answers

The solutions to the given quadratic equation can be determined using quadratic formula.

[tex]x= \frac{-b+- \sqrt{ b^{2} -4ac} }{2a} [/tex]

b =coefficient of x term = -2
a = coefficient of squared term = 1
c = constant term = 10

Using the values in the above formula we get:

[tex]x= \frac{2+- \sqrt{4-4(1)(10)} }{2(1)} \\ \\ x= \frac{2+- \sqrt{-36} }{2} \\ \\ x= \frac{2+-6i}{2} \\ \\ x=1+3i, x=1-3i [/tex]

So the correct answer to this question is option A

dr. Trekcir has $875 to invest. he invests some of it in account#1 paying 8% annual interest and the rest of it in account#2 paying 4% annual interest. After 1 year total interest is $49.00. find hou much is invested in each account

Answers

Here's what the equation would look like (I'm using the variable n for the investments):
0.08n + 0.04(875-n) = 49
Multiply both sides by 100:
8n + 3500 - 4n = 4900
Simplify:
4n+3500=4900
Isolate n:
4n = 1400
n = 350
8% invested: 350
4% invested: 525

N a class, 20% of the students are male and 80% female. among male students, 40% wears eyeglasses; among female students, 30% wear eye glasses. if we select a student from the class at random, what is the probability that the student wears eyeglasses

Answers

[tex]|\Omega|=100\%=1\\ |A|=40\%\cdot20\%+30\%\cdot80\%=0.4\cdot0.2+0.3\cdot0.8=0.08+0.24=0.32\\\\ P(A)=\dfrac{0.32}{1}=0.32=32\%[/tex]

This graph shows how much Marie earns babysitting compared with the number of hours she works select the correct statement about the graph

Answers

The answer is D 

The graph reflects that she is getting paid 10 dollars an hour

If you plot the points, you will see she makes 5 dollars every half hour

Answer:

Option D is the answer.

Step-by-step explanation:

This graph represents a linear function representing earnings of Marie at y axis and hours of working at x axis. To get the change in Marie's earnings for every 5 hours we will find the slope of the given line.

Slope of the line will define the rate of change in earning of Marie with respect to the time.

End points of the line at time t = 0 and t = 5 hours are (0, 0) and (5, 50).

Therefore slope = [tex]\frac{y-y'}{x-x'}=\frac{50-0}{5-0}=\frac{50}{5}=10[/tex]

So for each hour she works her earnings go up by $10.

Option D is the correct option.

The perimeter of the base of a regular quadrilateral prism is 60 cm, the area of a lateral face is 105 cm2. Find: the volume of the prism

Answers

Since the base is a regular quadrilateral, each of its 4 sides must have length
  s = P/4
  s = (60 cm)/4 = 15 cm

The area of one lateral face is the product of side length and height.
  A = s×h
  105 cm² = (15 cm)×h
Then the height of the prism is
  h = (105 cm²)/(15 cm) = 7 cm

The area of the base is then
  B = s²
  B = (15 cm)² = 225 cm²

The volume of the prism is the product of its base area and height.
  V = Bh
  V = (225 cm²)×(7 cm) = 1575 cm³


The volume is 1575 cm³.

Bruce bought a map that cost $7.35 he used a $10 bill to pay for his map what is the change

Answers

$2.65

You can get this by subtracting the 7.35 from the 10. 

10 - 7.35 = 2.65

The elevation is 12,000 feet. the altimeter reading in an airplane is 17.00 in hg. this pressure is equal to

Answers

The elevation is 12,000 feet. the altimeter reading in an airplane is 17.00 in hg. this pressure is equal to:
There are 29.92inHg in 1 atm
thus
17 inHg×(1 atm/29.92inHg)
=17/29.92
=0.5682 atm

Answer: 0.5682 atm

solve the system using substitution method
3x+y=6
2x-4y=10

Answers

[tex]\left\{\begin{array}{ccc}3x+y=6&|-3x\\2x-4y=10\end{array}\right\\\\\left\{\begin{array}{ccc}y=6-3x\\2x-4y=10\end{array}\right\\\\substitute\ y=6-3x\ to\ the\ second\ equation\\\\2x-4(6-3x)=10\\\\2x-4\cdot6-4\cdot(-3x)=10\\\\2x-24+12x=10\\\\14x-24=10\ \ \ |+24\\\\14x=34\ \ \ \ |:14\\\\x=\dfrac{34}{14}\to x=\dfrac{17}{7}\\\\substitute\ the\ value\ of\ x\ to\ first\ equation\\\\y=6-3\cdot\dfrac{17}{7}=6-\dfrac{51}{7}=\dfrac{42}{7}-\dfrac{51}{7}=-\dfrac{9}{7}[/tex]

[tex]\boxed{\left\{\begin{array}{ccc}x=\dfrac{17}{7}\\\\y=-\dfrac{9}{7}\end{array}\right}[/tex]
[tex]\begin{cases}&3x + y = 6 \\&2x - 4y = 10\end{cases}[/tex]

Multiply 4 to the first equation:
[tex]\begin{cases}&12x + 4y = 24 \\&2x - 4y = 10\end{cases}[/tex]

ADD Equation 1 to Equation 2 and find x:
[tex]\begin{aligned}&14x =34 \\&x= 34/14 \\& x = 17/7\end{aligned} [/tex]

Substitute x = 17/7 and find y:
[tex]\begin{aligned}&3x + y = 6 \\&3 (17/7) + y = 6 \\& 51/7 + y = 6 \\&y = -9/7\end{aligned} [/tex]

Answer: x = 17/7, y  = -9/7

5u exponent 7 - 21u exponent 7

Simply

Answers

Assuming the given is: 5u^7 - 21u^7
Since both algebraic terms are identical (both are using u^7), we can subtract the coefficients directly, as in: 5 - 21 = -16
Therefore, 5u^7 - 21u^7 = -16u^7

If the radius of a cone is doubled and the height is tripled, what happens to the volume?

Answers

This is the answer . Have a nice day

Find the derivative of f(x) = (1 + 5x2)(x − x2) in two ways. use the product rule. f '(x) = perform the multiplication first. f '(x) = do your answers agree? yes no

Answers

Answer:

The answers agree.

[tex]f^{\prime}(x) = - 20x^{3} + 15x^{2} - 2x + 1[/tex]

Step-by-step explanation:

The product rule is:

[tex]f(x) = g(x)h(x)[/tex]

[tex]f^{\prime}(x) = g^{\prime}(x)h(x) + g(x)h^{\prime}(x)[/tex]

In this problem, we have that:

[tex]f(x) = (1 + 5x^{2})(x - x^{2})[/tex]

So

[tex]g(x) = 1 + 5x^{2}[/tex]

[tex]g^{\prime}(x) = 10x[/tex]

[tex]h(x) = x - x^{2}[/tex]

[tex]h^{\prime}(x) = 1 - 2x[/tex].

[tex]f^{\prime}(x) = g^{\prime}(x)h(x) + g(x)h^{\prime}(x)[/tex]

[tex]f^{\prime}(x) = (10x)*(x - x^{2}) + (1 + 5x^{2})(1-2x)[/tex]

[tex]f^{\prime}(x) = 10x^{2} - 10x^{3} + 1 - 2x + 5x^{2} - 10x^{3}[/tex]

[tex]f^{\prime}(x) = - 20x^{3} + 15x^{2} - 2x + 1[/tex]

Multiplication first:

[tex]f(x) = (1 + 5x^{2})(x - x^{2})[/tex]

[tex]f(x) = x - x^{2} + 5x^{3} - 5x^{4}[/tex]

[tex]f(x) = -5x^{4} + 5x^{3} - x^{2} + x[/tex]

[tex]f^{\prime}(x) = -20x^{3} + 15x^{2} - 2x + 1[/tex]

Comparing the results, we can see that the derivatives obtained using the two methods are indeed the same. The answer is yes.

What's the function about?

The derivative of f(x) = (1 + 5x2)(x − x2) can be found using the product rule and by performing the multiplication first.

Using the product rule:

The product rule states that the derivative of f(x)g(x) is f′(x)g(x)+f(x)g′(x).

In this case, f(x) = 1 + 5x2 and g(x) = x − x2. So the derivative of f(x)g(x) is:

f′(x)g(x)+f(x)g′(x)

=(10x+10x3)(x−x2)+(1+5x2)(2x−2x3)

=10x2−10x3+10x3−10x4+2x−2x3+1+10x2−10x3

=−10x4+12x2+2x

Performing the multiplication first:

We can first multiply out the expression (1 + 5x2)(x − x2) to get:

x2−5x4+x3−5x3+x−x2

=−5x4+12x2+x

Then, we can take the derivative of this expression to get the same derivative as we found using the product rule:

f′(x)=−10x4+12x2+2x

Therefore, the derivative of f(x) = (1 + 5x2)(x − x2) is -10x4+12x2+2x, regardless of whether we use the product rule or perform the multiplication first.

Learn more about function

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The height of an object from a distance

Answers

y = height
x = distance from tower

tan(19.9) = y/x

tan(21.8) = y/(x-50)   ( x is 50 feet closer so subtract 50 from x)

find the tan of the angles:
tan19.9 = 0.362
tan21.8 = 0.400

replace those values in the equations:
0.362 = y /x
0.400 = y / (x-50)

rewrite to solve for height:
0.362x = y
0.400(x-50) = y  distribute the 0.400 and rewrite as 0.400x-20 =y

now solve:

0.362x = 0.400x-20

add 20 to each side:
0.362x +20 = 0.400x

subtract 0.362x from each side:

20 = 0.038x

divide both sides by 0.038
x = 20 / 0.038 = 526.3 feet

now that x is known replace x in the original equation and solve for y:

tan19.9 = y /x

0.362 = y / 526.3
y = 0.362 x 526.3
y = 190.5

the height of the tower is 190.5 feet

Determine whether the two figures are similar. If so, give the similarity ratio of the smaller figure to the larger figure. The figures are not drawn to scale

A. yes; 1:1:2
B. yes; 1:1:4
C. yes; 1:2:4
D. no

Answers

we have that
smaller figure
ha=8.7
ra=1.6

larger figure
hb=10.44
rb=1.92

ha/hb=8.7/10.44----> 0.83
ra/rb=1.6/1.92-------> 0.83

ratio smaller figure to the larger figure
1.6/1.92-------> divided by 1.6 both members
[1.6/1.6]/[1.92/1.6]-------> 1/1.2

the ratio ha/hb is equal to the ratio ra/rb
so
the smaller figure and the larger figure are similar
and the ratio smaller figure to the larger figure is equal to---->  1/1.2

the answer is
the option
yes 1/1.2

A technique used to rewrite a quadratic function in standard form to vertex form is

Answers

The vertex form of a quadratic function is given by
                                      [tex]f(x)=a(x-h)^{2}+k, [/tex]
where (h,k) is the vertex of parabola. In some literatures, the standard form of the quadratic equation is written as 
                                     [tex]f(x)=a x^{2} +bx+c[/tex] 
Therefore, in order to avoid the confusion, the first equation is taken as a vertex form. When the standard form is converted into the vertex form, the process is called completing the square. 

Answer:

completing the square.

Step-by-step explanation:

trust me

Iris is building a model of the Washington Monument. Her model measures 15 in. tall and is 1.5 in. wide at the base. The actual width measurement at the base of the Washington Monument is about 55 ft. About how tall is the Washington Monument?

Answers

Using how tall it is over how wide
=>tall/wide
The model 15in/1.5in
The actual x/55ft

Convert everything into the same units so 55ft to inches
There are 12in in 1ft
55ft * 12in/1ft
The ft cross out leaving in
55*12in= 660 in

So
15in/1.5in = x/660in
Now solve for x my multiplying both side by 660in
660in *15in/1.5in=x
x= 6600in tall




Answer: 550

Step-by-step explanation:Solve the proportion:  15 in./1.5 in. =  h/55 ft. The value of h is 550 ft. The Washington Monument is about 550 ft tall.

sq root of x +11 =15

Answers

Hello!

You can solve for x by subtracting 11 from 15 to get 4. Once you've got 4, you can power 4 by 2 (4²) to get 16 as your answer

x=16

So the value of x is 16
 
I hope this helps!
Remark
I take it you want to find x.

Square both sides.
(sqrt(x + 11))^2 = (15)^2
 x + 11 = 225  Subtract 11 from both sides.
x = 225 - 11
x = 214

Edit
This answer is edited to reflect which interpretation is correct. If you give out Brainlys (and you should) give it to Brick123. We all need them.

Sqrt(x) + 11 = 15   Subtract 11 from both sides.
sqrt(x) = 15 - 11
sqrt(x) = 4             Square both sides.
(sqrt(x)^2 = 4^2
x = 16


 

Oil-rich countries in the middle east cover about 4% of earth’s total land area but possess about 48% of the world’s known oil reserves. what is the main reason for the high concentration of reserves in this part of the world?

Answers

I'd say this high concentration is due to geological processes
Geological processes are things such as erosion, tectonic plate shifts, e.t.c.

The area of the parallelogram is 65 square miles. Find its base and height.

Answers

(base 13) (height 5)

(base 5) (height 13)
Area of parallelogram = base × height

Base = 13
Height = 5 

Or:

Base = 5
Height = 13

Hope this helped☺☺

What percent of the scores were between 71 and 96

Answers

Any more info? Please?

Ted researched the price of airline tickets and discovered a correlation between the price of a ticket and the number of miles traveled. After recording his data on a scatter plot, he determined the equation for the line of best fit is y = 300 + 0.45x. What does 0.45 represent in the equation? A) the lowest ticket price B) the number of miles traveled C) the expected change in the price of multiple tickets Eliminate D) the expected change in price of the ticket for each mile traveled

Answers

D) the expected change in price of the ticket for each mile traveled
Because it is a coloration between the two 
D) the expected change in price of the ticket for each mile traveled
Because it is a coloration between the two 

if an object is propelled upward from a height of s feet at an initial velocity of v feet per second h=-16t^2+96t+8 after how many seconds is the height 116 feet?

Answers

654 is the answer for this question

Find the area of the figure

Answers

You can solve each figure individually; the parallelogram, and the trapezoid.

The parallelogram, you can just do base * height. The base is 11 yards, and the height is 4 yards. 11 * 4 = 44 square yards.

Now for the trapezoid. If you split it up into a rectangle and a triangle, it becomes much more easier to solve. The rectangle and triangles can be made by splitting the figure down the center. This makes a rectangle with a length of 7 yards and a height of 8, and a triangle with a base of 7 yards and a height of 8 as well.

Solve for the area of both shapes.

The rectangle: Multiply length * height: 7 * 8 = 56 square yards

The triangle: Multiply base * height, and then divide by 2: 7 * 8 = 56
56 / 2 = 28 square yards

Now add the areas together.

28 + 56 + 44 = 128 square yards

Hope this helped!
These are the steps:
1. Find area of the trapezium.
2. Find area of the parallelogram.
3. Add the 2 areas together.


Step 1: Find the area of the trapezium:

Formula : area = 1/2 (a + b) h

Area = 1/2(7 + 14) (8) = 84 yd²


Step 2: Find the area of the parallelogram:

Formula : area = base x height

Area = 11 x 4 = 44 yd²


Step 3: Find the total area:

Total Area = 84 + 44 = 128 yd²

Answer: 128 yd²

Suppose that 44% of all Americans approve of the job the President is doing. The most recent Gallup poll consisted of a random sample of 1,400 American adults.

a. What is the mean of the sampling distribution?

b. What is the standard deviation of the sampling distribution (don't forget to justify the use of the formula)?

c. Describe the normal approximation for this sampling distribution (don't forget to justify this) You can simply write as N (mean, standard deviation)

d. What is the probability that the Gallup poll will come up with a proportion within three percentage points of the true 44%

Answers

a) Mean = n × p, n is 1400 and p is 0.44, using what you know 0.44 (p)× 1400 (n) = 616

b) SD = √ (n×p×q) n 1400 p is 0.44 and q = 1-p=1-0.44=0.56

You have been averaging 55 sales per day. Per our new policy, everyone needs to increase his or her sales per day by 10% in the next month. Rounding up, by next month you will need to be up to __________ sales.

Answers

The next month sales should be 1,815.

Given that,

You have been averaging 55 sales per day. increase his or her sales per day by 10% in the next month

Based on the above information, the calculation is as follows:

[tex]= 55 \times 1.10 \times 30 days[/tex]

= 1,815

Learn more: https://brainly.com/question/25914450?referrer=searchResults

Final answer:

To meet the new policy of a 10% increase in sales, you would multiply your current average sales by the increase percentage and round up to the nearest whole number. Starting from 55 sales, a 10% increase results in an additional 5.5 sales, which when rounded up equals 6. Therefore, you need to achieve 61 sales per day.

Explanation:

If you have been averaging 55 sales per day and need to increase your sales by 10%, you will first need to calculate the increase. To calculate a 10% increase, you multiply your current average sales (55) by the percentage increase (10%), expressed as a decimal (0.10). The increase in sales can be found by the formula:

Increase = Current Sales × Percentage Increase

For your sales:

Increase = 55 × 0.10 = 5.5 sales

Since you need to round up, the increase will be 6 sales when considering whole units, as you cannot sell half a unit.

Therefore, the new target sales per day will be:

New Sales Target = Current Sales + Increase

New Sales Target = 55 + 6 = 61 sales

By next month, you will need to be up to 61 sales per day after rounding up.

A standard dartboard has a diameter of 18 in. What is its area to the nearest square inch?

Answers

The meaning of the area is the measurement of a surface in this case a circle, which can be find by using the formula [tex]A= \pi r^{2} [/tex], where r is equal to the radius of the circle.

In this exercise is given that the diameter of a standard cardboard is 18 inches or a radius of 9 inches and it is asked to find its area. Therefore, to find the area of the circle you should substitute the value of the radius into the previous mention formula.

[tex]A= \pi r^{2}[/tex]
[tex]A= \pi (9 in)^{2} [/tex]
[tex]A= \pi (81 in^{2})[/tex]
[tex]A=254.47 in^{2} [/tex]

The area of the standard dartboard is 254.47 square inches or 254 square inches.





what is the solution to the equation 3sqrt(5x-4)=3sqrt(7x+8)

Answers

x = -6

However this is an extraneous solution since it would make the number under the sqrt a negative number. 

Answer:

The answer is:   'no solution'

Step-by-step explanation:

The given equation is:   [tex]3\sqrt{5x-4}=3\sqrt{7x+8}[/tex]

Dividing both sides of the equation by 3, we will get.....

[tex]\sqrt{5x-4}=\sqrt{7x+8}[/tex]

Taking square on both sides.....

[tex](\sqrt{5x-4})^2=(\sqrt{7x+8})^2\\ \\ 5x-4=7x+8\\ \\ 5x-7x=8+4\\ \\ -2x=12\\ \\ x=\frac{12}{-2}=-6[/tex]

Plugging this [tex]x=-6[/tex] back to the given equation......

[tex]3\sqrt{5(-6)-4}=3\sqrt{7(-6)+8}\\ \\ 3\sqrt{-34}=3\sqrt{-34}[/tex]

As we are getting a negative number inside the square root, so the equation becomes imaginary. Thus [tex]x=-6[/tex] is a restricted value.

Hence, there is 'no solution' for this equation.

What is the value of x in the equation –6 + x = –2?
8
4
–4
–8

Answers

the answer is 4.... -6+4=-2

If the volume is 56 1/4 cubic feet and the length is 7 1/2ft and the width is 3 3/4ft what is the height?

Answers

The height is 2. Multiply 7.5 by 3.75 and you should get 28.125. Divide 56.25 by 28.125 and you will get 2. If you want to check, multiply 2 by 7.5 by 3.75 and you will get 56.25.

write an expression that represents the difference between t and 8

Answers

An expression could be x= t-8
Hello there, and thank you for posting your question here on brainly.

Short answer: t - 8

Why?

When we are finding the difference between two numbers, we are subtracting. So, the difference between t and 8 would be t - 8.

Hope this helped you! ♥
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