A tire manufacturer is interested in testing the fuel economy for two different tread patterns. Tires of each tread type are driven for 1000 miles on each of 18 different cars. In a separate experiment, 18 cars were outfitted with tires with tread type A, and another 18 were outfitted with tires with tread type B. Each car was driven 1000 miles. The cars with tread type A averaged 23.95 mpg, with a standard deviation of 1.79 mpg. The cars with tread type B averaged 22.19 mpg, with a standard deviation of 1.95 mpg. Let μX represent the population mean mileage for tread type A and let μY represent the population mean mileage for tread type B.


Required:

Find a 99% confidence interval for the difference μXâμY. Round the answers to three decimal places.

Answers

Answer 1

Using the t-distribution, it is found that the 99% confidence interval for the difference is (0.058, 3.462).

We are given the standard deviation for the samples, hence, the t-distribution is used to solve this question.

The standard errors are given by:

[tex]s_A = \frac{1.79}{\sqrt{18}} = 0.4219[/tex]

[tex]s_B = \frac{1.95}{\sqrt{18}} = 0.4596[/tex]

For the distribution of differences, the mean and the standard error are given by:

[tex]\overline{x} = \mu_A - \mu_B = 23.95 - 22.19 = 1.76[/tex]

[tex]s = \sqrt{0.4219^2 + 0.4596^2} = 0.6239[/tex]

The interval is given by:

[tex]\overline{x} \pm ts[/tex]

The critical value for a two-tailed 99% confidence interval with 18 + 18 - 2 = 34 df is t = 2.7284.

Then:

[tex]\overline{x} - ts = 1.76 - 2.7284(0.6239) = 0.058[/tex]

[tex]\overline{x} + ts = 1.76 + 2.7284(0.6239) = 3.462[/tex]

The 99% confidence interval for the difference is (0.058, 3.462).

For more on the t-distribution, you can check https://brainly.com/question/16162795


Related Questions

Find the volume of a square based pyramid with a base length of 8 m and a height of 14 m.

Answers

[tex]V = \frac{1}{3} \times base \: area \: \times height \\ [/tex]

[tex]V = \frac{1}{3} \times {8}^{2} \times 14 \\ [/tex]

[tex]V = \frac{1}{3} \times 64 \times 14 \\ [/tex]

[tex]V = \frac{896}{3} \: \: \: {m}^{3} \\ [/tex]

Find fraction and a decimal between 0.66 and 3/4 .the fraction and decimal should be two different numbers

Answers

Answer:

Step-by-step explanation:

0.66=66/100       3/4=75/100

fraction between

67/100 68/100 69/100 70/100 71/100 72/100 73/100 74/100

               or                       or                   or                      or

             17/25                  7/10               18/25               37/50

decimal between

0.67  0.68 0.69 0.70 0.71 0.72 0.73 0.74

What is the surface of this shape

Answers

Answer:

Find the area of all of the different shapes (2D)

and then add them up together to find the surface area.

3×2

6×2

6×2

5×3

6×3

1×3

1×4

1×4

4×3

Then you add them up together.

6+12+12+15+18+3+4+4+12=ANS.

What is the equation of a line that is parallel to the line 2x + 5y = 10 and passes through the point (–5, 1)? Check all that apply. In addition to the Privileges and Immunities Clause, Article IV, Section 2 includes the

Answers

Hello!

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

2x+5y=10

We want to turn this equation into y=mx+b form:

5y=-2x+10

Divide both sides by 5:

y=-2/5x+2

Now, the equation of the line parallel to it:

Remember, parallel lines have the same slope.

So these two lines have the same slope (-2/5)

Now, use Point-Slope form:

y-y1=m(x-x1)

y=1=-2/5(x-(-5)

y-1=-2/5(x+5)

y-1=-2/5x-2

y=-2/5x-2+1

y=-2/5-1

Hence, this is the required solution. I hope you find it helpful!

~SparklingFlower

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

Help pls I have no clue what this is

Answers

Answer:

  b = 76°

Step-by-step explanation:

Angle JIK is the smaller acute angle in one of four congruent right triangles. Angle GHK is the larger acute angle in those triangles, marked as 60°. The sum of the acute angles in a right triangle is 90°, so you have ...

  60° +(b-46)° = 90°

  14° +b = 90° . . . . . . . simplify

  b = 76° . . . . . . . subtract 14°

(a) A box contains 7 red balls, 6 white balls, and 7 black balls. Two balls are drawn at random from the box (with replacement of the first before the second is drawn). What is the probability of getting a red ball on the first draw and a white ball on the second

Answers

Answer:

Step-by-step explanation:

20=total marbles

  7/20 × 6/20=  21/400   or 5.25%

   red     white

3^4x-1=15
Need help with this log question

Answers

Answer:

x=16/81

Step-by-step explanation:

3^4x-1=15

81x-1=15

81x=15+1

81x+16

divide both sides by 81

x=16/81

Which could be the first 4 terms of an arithmetic sequence ?

Answers

Awnser: B

Explain: if you line up and set up a graph with the numbers you will get b to be the awnser

(Can I get brainliest

Complete the table for the provided graph.

Answers

Answers on following order: 5, 2, 4, 2, 8, 0

Can someone please help me

Answers

Step-by-step explanation:

it will be around $90.86

Answer:

No. of adults who answered 'yes'

= 20% × 1073

= 214.6

Total amount of money paid

= (18%×$77)+$77

= $13.86+$77

= $90.86

Help help help help hell

Answers

Answer:

m = N - f

Step-by-step explanation:

The original equation:

N = m + f

if we have to solve for m, then we have to isolate it, so subtract f from both the sides and that would be the answer.

Hope this helps!

A school wants to investigate the amount of exercise students do.
There are 1200 students at the school.
a Suggest a sensible number of students to be sampled.

Answers

Answer:

100-200     Step-by-step explanation: yes 600 is half the students most of them are going to be in class

Which expressions are equivalent to (1/3x+2x−5/3x)−(−1/3x+5) ? Select all correct expressions. −4x+5+3x 5−x 4x−5−3x x−5

Answers

Answer:

its x-5 and 4x-5-3x

Step-by-step explanation:

I took the test

Domain:
Range:
HELP RQ

Answers

i'm not too sure, as i'm learning this at the moment too. correct me if i'm wrong but wouldn't both be (infinity, infinity) ?? since there's arrows meaning its infinite

-4√-32

answer it please ok thanks

Answers

Answer:

Step-by-step explanation:

4 √(-32) =

22.627417

HOW DO I FIND QR

PLEASE HELP

Answers

Solution: For finding QR we need to apply Pythagoras Theorem

What is Pythagoras Theorem ?

ans : Pythagoras Theorem is the sum of square of two sides which is equal to the third side or the hypotenuse. This formula is valid oy incase of Right-Angled Traingle because one of three angles here is 90°

According to this law let's apply it in the diagram shown here.

(Hypotenuse)² = (Adjacent)² + (Opposite)²

(PR)² = (QR)² + (PQ)²

(5x - 2)² = (QR)² + (3x - 1)²

(QR)² = (5x - 2)² - (3x - 1)²

After factorising both of them we get

(QR)² = 25x² - 20x + 4 - (9x² - 6x + 1)

(QR)² = 25x² - 20x + 4 - 9x² + 6x - 1

(QR)² = 16x² - 14x + 3

QR = √(16x² - 14x + 3)

So, QR is √(16x² - 14x + 3)

Need helpPlzzzzzzzzzzzzzzzz

Answers

Answer:

2

Step-by-step explanation:

10. If pointer 1 is spun and then pointer 2 is spun, determine the probability of landing on a color other than red on both spins. The probability is (Type an integer or a simplified fraction.)​

Answers

Answer:

Answer below

Step-by-step explanation:

1/8 is correct

in pic

_________________________________________

(Hope this helps can I pls have brainlist (crown)☺️)

Is (1,5) a solution to this system of equations?
y=

3x+7
y=3x+2

Answers

Answer:

no, there is no solution

Step-by-step explanation:

put it in desmos, but the slopes are the same, so they are parallel and never touch. So, no solution.

PLEASE HELP! I"LL MARK BRAINLIEST!!!!


△ABC is translated left 3 units to form the image ∆A′B′C′.

What are the coordinates of the vertices of ∆A′B′C′ ?

Enter your answer by filling in the boxes.

A′ =

B′ =

C′ =

Answers

Answer:

a is -1, -2

b is -1, 2

c is 2, 2

Step-by-step explanation:

i hope i helped

WILL GIVE BRAINLIEST
(x + 6) in
(3x + 2) in
12 in
The perimeter of this triangle is___in.

Answers

Answer:

28 inches

Step-by-step explanation:

To find the value of x you put them into an equation of: (x+6) = (3x+2), this would let you find that x=2, since 2+6 = 6+2. Once you've plugged that in all you need to do is add together all the sides, and since side A and side B are both 8 you do 12+16 to get the perimeter of 28 inches.

8.) The grocery store is having a sale on frozen vegetables. 4 bags are being sold for $11.96. At this rate, what is the cost of:
a) 1 bag
b) 9 bags

Answers

a) 1 bag is $2.99

b) 9 bags are $26.91.

$11.96/4 is 2.99

So one bag costs $2.99 and for any rest of number of bags we just multiply that number by 2.99!!

Hope this helps. :)

Answer:

a) $2.99

b) $26.91

Step-by-step explanation:

Since 4 bags cost $11.96, you can find the price of an individual bag by dividing $11.96 by 4.

Since

$11.96 / 4 = $2.99

One bag costs $2.99

To find the price of 9 bags, just multiply 2.99$ by 9:

$2.99 * 9 = $26.91

135 rational or irrational ​

Answers

Answer:

Rational

Step-by-step explanation:

I hope this helps!

It is an Irrational number

There are 13 books on a shelf. 7 of these books are new. The rest of them are used.

Answers

Answer:

6 of them are used books

Step-by-step explanation:

6+7=13. 7 new book and add 6 more book that will be used, it will equal out in addition = 13

An experiment is conducted examining the effects of a new type of toothpaste on reducing cavities. Individuals in the treatment condition are given the new toothpaste; individuals in the control condition are given the standard toothpaste, but are told that they're receiving the new toothpaste. At the end of the experiment, the control group participants demonstrate a slightly higher decline in cavities. This is an example of a(n):____.
a. Wording bias.
b. Voluntary response bias.
c. Over-sampling effect.
d. Placebo effect.
d. Hawthorne effect.

Answers

The experimental effect highlighted by the scenario described would most likely be an example of placebo effect.

An observed change in the control group which are being given the placebo would have been triggered due to psychological expectation based on the information given. Hence, this is called the placebo effect.

The standard toothpaste was not suppose to cause decline in cavities, however, since the group have been told that they we given the new toothpaste which is said to reduce cavities, this could trigger a psychological change hence causing them to have higher cavity decline.

Learn more : https://brainly.com/question/25704508

pls answer fast

Write an equation of the line that passes through (0, -5) and is perpendicular to the line y =-4/5x

Answers

Answer:

I am pretty sure its y={5}/{4}x-5

Step-by-step explanation:

Please look at picture for question.

Answers

Answer:

[tex]\frac{-1}{5}m -\frac{4}{5}[/tex]

Step-by-step explanation:

Combine the like terms (2/5) and (-3/5) m

This will give you -1/5

place the remainder of the equation.

if you like my answer, please mark me brainliest !! thanks !! <3

a simple random sample of 60 items resulted in a sample mean of 80.

Answers

Answer:

(c) The effect of a larger sample size on the margin of error is that the margin of error will increase.

Step-by-step explanation:

A breakfast cereal producer makes its most popular product by combining just raisins and flakes in each box of cereal. The amounts of flakes in the boxes of this cereal are normally distributed with a mean of 370\,\text{g}370g370, start text, g, end text and a standard deviation of 24\,\text{g}24g24, start text, g, end text. The amounts of raisins are also normally distributed with a mean of 170\,\text{g}170g170, start text, g, end text and a standard deviation of 7\,\text{g}7g7, start text, g, end text.
Let T=T=T, equals the total amount of product in a randomly selected box, and assume that the amounts of flakes and raisins are independent of each other.
Find the probability that the total amount of product is less than 575\,\text{g}575g575, start text, g, end text.
You may round your answer to two decimal places.
P(T<575)\approx

Answers

Using the normal distribution, it is found that there is a 0.9192 = 91.92% probability that the total amount of product is less than 575 g.

In a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

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

It 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, which is the percentile of X.When two normal variables are added, the mean is the sum of the means while the standard deviation is the square root of the sum of the variances.

In this problem, the product is composed by flakes and raisins, and we have that:

[tex]\mu_F = 370, \sigma_F = 24, \mu_R = 170, \sigma_R = 7[/tex]

Hence, the distribution for the total amount of product has mean and standard deviation given by:

[tex]\mu = \mu_F + \mu_R = 370 + 170 = 540[/tex]

[tex]\sigma = \sqrt{\sigma_F^2 + \sigma_R^2} = \sqrt{24^2 + 7^2} = 25[/tex]

The probability that the total amount of product is less than 575 g is the p-value of Z when X = 575, hence:

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

[tex]Z = \frac{575 - 540}{25}[/tex]

[tex]Z = 1.4[/tex]

[tex]Z = 1.4[/tex] has a p-value of 0.9192.

0.9192 = 91.92% probability that the total amount of product is less than 575 g.

A similar problem is given at https://brainly.com/question/22934264

The perimeter of a rectangle is 40 inches. If the width of the rectangle is 7 inches, what is the length?

Answers

Answer:

l=13in

Step-by-step explanation:

hope this helps

Answer:

13

Step-by-step explanation:

(40-7*2)/2=20-7=13

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