High school students from track teams in the state participated in a training program to improve running times. Before the training, the mean running time for the students to run a mile was 402 seconds with standard deviation 40 seconds. After completing the program, the mean running time for the students to run a mile was 368 seconds with standard deviation 30 seconds. Let X represent the running time of a randomly selected student before training, and let Y represent the running time of the same student after training. Which of the following is true about the distribution of X-Y?a. The variables X and Y are independent, therefore, the meanis 34 seconds and the standard deviation is 10 seconds.b. The v ales X and Y are independent therefore, the meanis 34 seconds and the standard deviation is 50 secondsc. The variables X and Y are not independent, therefore, the standard deviation is 50 seconds and the mean cannot be determined with the information given.d. The variables and are not independent, therefore, the meanis 3 seconds and the standard deviation cannot be determined with the information givene. The variables X and Y We not independent, therefore, neither the mean nor the standard deviation can be determined with the informantion given.

Answers

Answer 1

Answer:

b. The values X and Y are independent therefore, the mean is 34 seconds and the standard deviation is 50 seconds

Step-by-step explanation:

Subtraction between normal variables:

When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

Before the training, the mean running time for the students to run a mile was 402 seconds with standard deviation 40 seconds.

This means that [tex]\mu_X = 402, \sigma_X = 40[/tex]

After completing the program, the mean running time for the students to run a mile was 368 seconds with standard deviation 30 seconds.

This means that [tex]\mu_Y = 368, \sigma_Y = 30[/tex]

Which of the following is true about the distribution of X-Y?

They are independent, so:

[tex]\mu = \mu_X - \mu_Y = 402 - 368 = 34[/tex]

[tex]\sigma = \sqrt{\sigma_X^2+\sigma_Y^2} = \sqrt{40^2+30^2} = 50[/tex]

This means that the correct answer is given by option b.

Answer 2

The values X and Y are independent therefore, the mean is 34 seconds and the standard deviation is 50 seconds.

What is the subtraction between normal variables?

The two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

Before the training, the mean running mean  time for the students to runing a mile was 402 seconds with standard deviation 40 seconds.

That is the [tex]\mu_x=402 , \sigma_x=40[/tex]

That is the after completing the program, the mean running time for the students to run a mile was 368 seconds with standard deviation 30 seconds.

That is [tex]\mu_y=368,\sigma_y=30[/tex]

which of the following is true about the distribution of X-Y?

They are independent

Therefore we get,

[tex]\mu=\mu_x-\mu_y=402-368=34[/tex]

[tex]\sigma=\sqrt{\sigma_x^2-\sigma_y^2}\\\sigma=\sqrt{40^2-30^2}\\\sigma =50[/tex]

Therefore the option b is correct.

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This means that the correct answer is given by option b.


Related Questions

Reflect (‐10,4) across the x‐axis what is the reflected ordered pair​

Answers

Answer:

(-10, -4)

Step-by-step explanation:

That is the ordered pair

Tickets to the theater cost $8.00 for adults and $3.00 for children. A group of 2
total people showed up to the theater. They spent $93.00 total on tickets. How
many adults and children were in the group?

Answers

Answer: 9 adults 7 children

Step-by-step explanation:

Cedar Point has 17 roller coasters. If you want to ride at least 15 of them, how many different combinations of roller coasters can you ride? NO LINKS!!!​

Answers

Answer:   154

================================================

Explanation:

I'll be using the formula

[tex]_n C _r = \frac{n!}{r!*(n-r)!}[/tex]

which is the nCr combination formula. We use nCr instead of nPr because the order of coasters doesn't matter. The whole time, the value of n stays fixed at n = 17 which is the total number of coasters to pick from.

While n is constant, the value of r will vary. It ranges from r = 15 to r = 17 inclusive of both endpoints. In other words, r will take on values from the set {15,16,17}. So we have three cases to consider. The r value is how many coasters we select. This is due to the "at least 15" which means "15 or more".

-----------------------

If you ride r = 15 coasters, then we have the following number of combinations

[tex]_n C _r = \frac{n!}{r!*(n-r)!}\\\\_{17} C _{15} = \frac{17!}{15!*(17-15)!}\\\\_{17} C _{15} = \frac{17!}{15!*2!}\\\\_{17} C _{15} = \frac{17*16*15!}{15!*2!}\\\\_{17} C _{15} = \frac{17*16}{2!}\\\\_{17} C _{15} = \frac{17*16}{2*1}\\\\_{17} C _{15} = \frac{272}{2}\\\\_{17} C _{15} = 136\\\\[/tex]

There are 136 ways to ride exactly 15 coasters (when selecting from a pool of 17 total). The order doesn't matter.

We'll use this result later, so let x = 136.

-----------------------

If r = 16, then we follow the same steps as above. You should get 17C16 = 17

There are 17 ways to ride 16 coasters where order doesn't matter. Effectively this is the same as saying "there are 17 ways of picking a coaster that you won't ride"

Let y = 17 so we can use it later

-----------------------

Lastly, if r = 17, then nCr = 17C17 = 1 represents one way to ride all 17 coasters where order doesn't matter.

Let z = 1

-----------------------

Add up the values of x, y, and z to get the final answer

x+y+z = 136+17+1 = 154

The number of new customers n that visit a dry cleaning shop in one year is directly related to the
amount a in dollars) spent on advertising. This relationship is represented by n3 = 13,824a. To
attract 480 new customers, how much should the owners spend on advertising during the year?

Answers

Answer:

$15,264 cost amount on new advertising.

Shown as new equation that includes (original + new customer base)

n3=15264a

Step-by-step explanation:

First we have to find original amount of customers as 3 represents a multiple of n

n3=13824a

n3 means n x 3 then customer base is one third

= 1/3 x 13,824  = 4608 original customers per year

= 4608 original customers +480 new customers

4608 + 480 = 5088 total orig+initial  customers

5088 x 3 = 15264 cost

= ($)15,264 cost

new equation

n3=15264a

Jerome purchased a 4-year old car for $12,000. He was told this make a model depreciates exponentially at a rate of 5.7% each year. What was the original price to the nearest hundred dollars?
Group of answer choices

$19,300

$15,200

$12,500

$17,500

Answers

19,300 5.7 by 12,000 just makes scene

Plz help me well mark brainliest!!

Answers

Answer:

735 mm³

Step-by-step explanation:

49 x 15 = 735

Answer:

735mm

Step-by-step explanation:

Need help Math Question Multiple Choice!

Answers

Given :

A function f(x) for different range of x.

To Find :

The value of f( -3 ) .

Solution :

We have to find the value of function at x = -3.

Now, in the given figure -3 lies in range x ≤ -2 and definition of function at that range is :

[tex]f(x) = \dfrac{2}{x}[/tex]

So, putting value of x = -3 in above equation, we get :

[tex]f(-3) = \dfrac{2}{-3} \\\\f(-3) = \dfrac{-2}{3}[/tex]

Hence, this is the required solution.

Write the equation of the linear relationship in slope-intercept form.

Answers

Answer:

y = 1/3x + 70/3

Step-by-step explanation:

2 points on the graph:

(20, 30) and (50, 40)

Slope:

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

m=(40 - 30)/(50 - 20)

m= 10/30

m= 1/3

Slope-intercept:

y - y1 = m(x - x1)

y - 30 = 1/3(x - 20)

y - 30 = 1/3x - 20/3

y = 1/3x + 70/3

If a population is
a sample of the population could be
O A. ninth-graders at Peak School; all students at Peak School
B. math teachers; the entire school faculty
O C. people who purchased shoes; all customers
O D. all citizens; registered voters

Answers

Answer:

Step-by-step explanation:

D.all citizens; registered voters

I need the answer fast pls

Answers

1/8 is the mode. It appears most often

Answer:

Option A, 1/8 pound would be the correct answer

Step-by-step explanation:

Since mode of the data is the number in the data that occurs the most, if noticed 1/8 occurs 4 times in the data set given and hence is the mode of the data set

Hope this helps!

Need help with this question. 20 points

Answers

9514 1404 393

Answer:

  3

Step-by-step explanation:

For x > 0, the function f(x) is ...

  f(x) = 3x -4 . . . . . . . . for x > 0

Translating this down 1 unit makes it ...

  g(x) = f(x) -1 = 3x -5

The rate of change for any interval such that x > 0 in the whole interval is the coefficient of x: 3.

The rate of change on the interval is 3.

__

If you like, you can find the rate of change from ...

  m = (g(5) -g(2))/(5 -2) = (10 -1)/3 = 9/3 = 3

The rate of change is 3.

A cone has a radius of 5 ft and a height of 15 ft. It is empty and is being filled with water at a constant rate of 15 15 ft 3 ft3 / sec sec . Find the rate of change of the radius of the surface of the water when the radius of the surface of the water is 2 2 ft. (You must also include the units)

Answers

Answer:

[tex]\frac{dr}{dt}=0.11062ft/sec[/tex]

Step-by-step explanation:

From the question we are told that:

Radius [tex]r=5ft[/tex]

Height [tex]H=15ft[/tex]

Rate [tex]R=15ft/3sec =5ft/s[/tex]

Surface Radius [tex]R_{surf}=2.2ft[/tex]

Generally the equation for Volume is mathematically given by

 [tex]V=\frac{1}{3}\pi*r^2h[/tex]

Since radius to height ratio gives

 [tex]\frac{r}{h}=\frac{5}{15}[/tex]

 [tex]\frac{r}{h}=\frac{1}{3}[/tex]

 [tex]h=3r[/tex]

Therefore

 [tex]V=\frac{1}{3}\pi*r^2(3r)[/tex]

 [tex]V=\pi r^3[/tex]

Generally the equation for Change of Volume is mathematically given by

 [tex]\frac{dv}{dt}=\pi \frac{d}{dt}(r^3)[/tex]

 [tex]\frac{dv}{dt}=\pi 3*r^2 \frac{dr}{dt}[/tex]

 [tex]\frac{dv}{dt}=\pi 3*(2.2)^2 \frac{dr}{dt}[/tex]

 [tex]\frac{dr}{dt}=\frac{5}{45.62}[/tex]

 [tex]\frac{dr}{dt}=0.11062ft/sec[/tex]

Segment AB is a ____

Answers

The segment is referred to as a diameter
I’m not quite sure of what kinda answer this is looking for.. but it’s the diameter of the circle

evaluate this expression 5+3(8-2)

Answers

Answer:86 Step-by-step explanation:

Define the term volume​

Answers

Answer:

Volume: The space which fills up a certain object on the inside.

prove that; tan20+4sin20= square root of3

Answers

tan( 20 ) + 4 Sin( 20 ) =

( Sin( 20 ) / Cos( 20 ) ) + 4 Sin( 20 ) =

Sin( 20 ) + 4 Sin( 20 ).Cos( 20 ) / Cos( 20 ) =

Sin( 20 ) + 2 × 2 Sin(20).Cos(20)/ Cos(20) =

Sin( 20 ) + 2 × Sin( 40 ) / Cos( 20 ) =

Sin( 20 ) + 2Sin( 40 ) / Cos( 20 ) =

Sin( 20 ) + 2Cos( 50 ) / Cos ( 20 ) =

Sin( 20 ) + 2Cos( 20 + 30 ) / Cos( 20 ) =

________________________________

2 × Cos( 30 + 20 ) =

2 × [ Cos(30).Cos(20) - Sin(30).Sin(20) ] =

2 × [ √3/2 × Cos(20) - 1/2 × Sin(20) ] =

√3 Cos(20) - Sin(20)

_________________________________

Sin( 20 ) + 2Cos ( 20 + 30 ) / Cos( 20 ) =

Sin( 20 ) + 3 Cos(20) - Sin(20) / Cos(20) =

Sin(20) - Sin(20) + √3 Cos(20) / Cos(20) =

0 + √3 Cos(20) / Cos(20) =

√3 Cos(20) / Cos(20) =

Cos(20) simplifies from the numerator and denominator of fraction

√3 × 1 / 1 =

√3

And we're done ....

Match the volume of a prism to the correct dimensions of a rectangular prism
Volume of Rectangular Prism
Dimensions of Rectangular Prism
31.3ft:51
6 ft. 2 ft. 4
7.2 ft. 21
6.5 ft. 2 st
48 cubic feet
60 cubic feet
45 cubic feet
28 cubic feet

Answers

Answer:

3 ft, 3ft, 5ft => 45 cubic feet

6 ft, 2 ft, 4 ft => 48 cubic feet

7 ft, 2 ft, 2 ft => 28 cubic feet

6 ft, 5 ft, 2 ft => 60 cubic feet

Step-by-step explanation:

Recall: formula for volume of a rectangular prism is given as, V = L × W × H

✔️Volume of rectangular prism with the following dimensions:

L = 3 ft

W = 3 ft

H = 5 ft

V = 3 × 3 × 5

V = 45 cubic feet

✔️Volume of rectangular prism with the following dimensions:

L = 6 ft

W = 2 ft

H = 4 ft

V = 6 × 2 × 4

V = 48 cubic feet

✔️Volume of rectangular prism with the following dimensions:

L = 7 ft

W = 2 ft

H = 2 ft

V = 7 × 2 × 2

V = 28 cubic feet

✔️Volume of rectangular prism with the following dimensions:

L = 6 ft

W = 5 ft

H = 2 ft

V = 6 × 5 × 2

V = 60 cubic feet

Simplify: 3-2
A. -9
B. -6
C.1/9
D.1/6​

Answers

Answer:

1/9

Step-by-step explanation:

3 ^ -2

The negative in the exponent means to bring it to the denominator

1/ 3^2

1/9

Answer:

C. 1/9

Step-by-step explanation:

POSSIBLE POINTS 50
Mr Franklin needs to pay for his three kids to go to college. He figured out that college will cost an average of
$50,000 per year per child when they are ready to go to college. To pay for this, Mr. Franklin bought a cylindrical
gas truck, The truck is 40 feet long and the radius of the base is 60 inches, Gas has a density of five pounds per
cubic foot. Mr. Franklin makes $2.50 per pound of gas when he sends a delivery. How many trips of full tanks of
gas will Mr. Franklin have to send to pay for his three kids to go to four years of college each?
Be sure to label each step and show all work. Don't forget units.
a) Find the volume of the cylinder
b) Find the mass of the gas in one truckload by using the density formula
c) Find the amount of money one truckload will generate.
d) Find the amount of money four years of college will cost for Mr. Franklin's three children.
e) Find the amount of trips it will take Mr. Franklin to make enough money to pay for college,
5
x Clear
Und

Answers

Answer:

2500

Step-by-step explanation:

Assets Liabilities
Checking and Savings $275
Owe $415 on graduation items
Rare Baseball Cards $210 Borrowed $50 from mom
Check for work done for a neighbor $19

This is a list of Karen's assets and liabilities.

What is her net worth?

$1
$39
$275
$294

Answers

Answer:

Step-by-step explanation:

$39

The net worth should be considered as the $39.

Calculation of the net worth;

We know that

Net worth = Total assets - total liabilities

here,

total assets = checking & savings + baseball card + check for work done

= $275 + $210 + $19

= $504

And, the total liabilities = owe + borrowed

= $415 + $50

= $465

So, the net worth be

= $504 - $465

= $39

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Consider the following statements about the effect of different values of a on the function y = ab^x. Which one of the statements, if any, is incorrect?

A. Values of a such that |a| > 1 will vertically stretch the graph of y = b^x.
B. Values of a such that 0 < |a| < 1 will vertically compress the graph of y = b^x.
C. Negative values of a will reflect y = b^x across the y-axis.
D. All of the above statements are correct.

Answers

All statements are correct.

No, There is no any sentences are incorrect.

Hence, All sentences are correct.

What is mean by Function?

A relation between a set of inputs having one output each is called a function. and an expression, rule, or law that defines a relationship between one variable (the independent variable) and another variable (the dependent variable).

Given that;

Consider the following statements about the effect of different values of a on the function,

⇒ y = a bˣ

Now, We know that;

For the value of a such that |a| > 1

The graph of y = bˣ is vertically stretch.

And, For the values of a such that 0 < |a| < 1;

The graph of y = bˣ is vertically compress.

And, When we take negative value of a.

Then, Function reflect y = bˣ across the y-axis.

Thus, There is no any sentences are incorrect.

Hence, All sentences are correct.

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15 points
Right triangle trigonometry

Answers

Answer:

Step-by-step explanation:

take theta as reference angle

tan theta=opposite/adjacent

=15/8

Answer:

option B

Step-by-step explanation:

First find opposite side using Pythagoras theorem:

[tex]17^2 = 8^2 + opposite^2 \\\\opposite^2 = 289 - 64 = 225\\\\opposite = 15[/tex]

Therefore,

          [tex]tan \theta = \frac{opposite}{adjacent} = \frac{15}{8}[/tex]

HELPP HELPPP ????pls

Answers

Answer:

B) the interquartile range of the data set is 2

Step-by-step explanation:

To find the interquartile range you have to subtract Q3-Q1. Which would be 3-1 and the answer is 2.

Hope this helped :)

Work Time Lost due to Accidents At a large company, the Director of Research found that the average work time lost by employees due to accidents was hours per year. She used a random sample of employees. The standard deviation of the sample was hours. Estimate the population mean for the number of hours lost due to accidents for the company, using a confidence interval. Assume the variable is normally distributed. Round intermediate answers to at least three decimal places. Round your final answers to the nearest whole number.

Answers

Answer:

(95.215 ; 100.785)

(95 ; 101) (nearest whole number)

Step-by-step explanation:

To obtain the confidence interval :

Mean ± margin of error

Mean = 98 hours

Margin of Error = Tcritical * (s/√n)

samole standard deviation, s = 5.6 hours

df = n - 1 = 18 - 1 = 17

Tcritical at (0.05, df = 17) = 2.110

Hence ;

Margin of Error = 2.110 * (5.6/√18) = 2.785

Confidence interval :

98 ± 2.785

Lower boundary = 98 - 2.785 = 95.215

Upper boundary = 98 + 2.785 = 100.785

(95.215 ; 100.785)

Helaine graphed the equation 12x−4y=3. What was the slope of Helaine’s line?

Answers

Answer:

The slope is 3

Step-by-step explanation:

12x−4y=3

Solve for y

Subtract 12x from each side

-12x +12x−4y=-12x+3

-4y = 12x+3

Divide each side by -4

-4y/-4 = -12x / -4 +3/-4

y = 3x -3/4

This is in slope intercept form

y = mx+b where m is the slope and b is the y intercept

The slope is 3

Answer:

The slope is 3

Step-by-step explanation:

12x−4y=3

Solve for y

Subtract 12x from each side

-12x +12x−4y=-12x+3

-4y = 12x+3

Divide each side by -4

-4y/-4 = -12x / -4 +3/-4

y = 3x -3/4

This is in slope intercept form

y = mx+b where m is the slope and b is the y intercept

The slope is 3

You deposit $500 in an investment account. The rate of growth is 6% a year. If you make no further deposits or withdrawals, and the investment is allowed to grow uninhibited, how long will it take for your investment to reach $1,500? Round to the nearest tenth.
A. 18.3 years
B. 45.1 years
C. 27.6 years
D. 8.0 years

Answers

Try B it might be correct and double check!

With the given compound interest of 6% per year to reach the investment at $1500, it will take 18.3. years thus option (A) is correct.

What is compound interest?

Compound interest is applicable when there will be a change in principal amount after the given time period.

For example, if you give anyone $500 at the rate of 10% annually then $500 is your principle amount. After 1 year the interest will be $50 and hence principle amount will become $550.

As per the given,

Principle amount P = $500

Rate of interest r = 6% annually

Total investment = P(1 + r)^T

1500 = 500(1 + 0.06)^T

300 = 1.06^T

Take natural logs on both sides

ln300 = T ln1.06

T = 18.3 years

Hence "With the given compound interest of 6% per year to reach the investment at $1500, it will take 18.3. years".

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help asap will be marked BRAINIEST

Answers

Answer:

∠BAC = 75°

Step-by-step explanation:

just subtract angle BAD from angle CAD

BAC=75

Just subtract angle BAD From Angle CAD

Value of x ?
A 70
B 60
C 50
D 40
please ignore the 90

Answers

Answer:

A 70°

Step-by-step explanation:

Angle of the triangle

=180-60-60

=60°

x= 180-60-50

=120-50

=70°

2) Use the law of sines to find the length of SR
sin⁡(A)/a=sin⁡(B)/b=sin⁡(C)/c

Answers

Answer:

take 28 degree as reference angle

using sine angle

sin28=p/h

0.46=10/h

0.46h=10

h=10/0.46

h=21.73

therefore hypotenuse =21.73

again using sine rule

take 25 degree as reference angle

sin 25=p/h

0.42=SR/21.73

0.42*21.73=SR

9.12=SR

9.1=SR

Step-by-step explanation:

A line representing Car B would have a parallel slope if:

Answers

Answer:

you add an image

Step-by-step explanation:

Answer:

... if it had the same slope in the y=mx+b equation where m is the slope and x is just x and b is the y-intercept

Step-by-step explanation:

say Car A had the equation y=2x+3- Car B would also have to have be y=2x but the y intercept could be any value

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