1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
dolphi86 [110]
3 years ago
8

A supplier of a certain car parts chain of stores wants to estimate the average length of time car owners plan to keep their car

s. From the past it is known that the standard deviation of the length of times car owners plan to keep their cars is 6.5 years. A random sample of 25 car owners results the average length of time of 7.2 years. Calculate and interpret a 99% confidence interval for the average length of time all car owners plan to keep their cars.
Mathematics
1 answer:
____ [38]3 years ago
7 0

Answer:

The 99% confidence interval for the average length of time all car owners plan to keep their cars is between 3.85 years and 10.55 years.

Step-by-step explanation:

We have that to find our \alpha level, that is the subtraction of 1 by the confidence interval divided by 2. So:

\alpha = \frac{1-0.99}{2} = 0.005

Now, we have to find z in the Ztable as such z has a pvalue of 1-\alpha.

So it is z with a pvalue of 1-0.005 = 0.995, so z = 2.575

Now, find the margin of error M as such

M = z*\frac{\sigma}{\sqrt{n}}

In which \sigma is the standard deviation of the population and n is the size of the sample.

M = 2.575*\frac{6.5}{\sqrt{25}} = 3.35

The lower end of the interval is the sample mean subtracted by M. So it is 7.2 - 3.35 = 3.85 years

The upper end of the interval is the sample mean added to M. So it is 7.2 + 3.35 = 10.55 years

The 99% confidence interval for the average length of time all car owners plan to keep their cars is between 3.85 years and 10.55 years.

You might be interested in
Chicago Avenue is parallel to Ontario Street what is the relationship between angles five and seven?
Triss [41]

Answer:

they are corresponding angles

6 0
3 years ago
Kendra was asked to find the number of students who planned to attend the evening sympothy performance. She was told that 40 per
ch4aika [34]

Answer:

It's B

Step-by-step explanation:

4 0
2 years ago
Read 2 more answers
Find the area of the polygon.
zhannawk [14.2K]

Answer:

820 m^{2}

Step-by-step explanation:

5 0
2 years ago
A cone and its dimensions are shown in the diagram. Which measurement is closest to the volume of the cone in cubic inches?
Diano4ka-milaya [45]
20 Cubic Inches^3.

Explanation:

The volume of a cone is Pi*R^2*H*1/3

We know the height, but we are given the diameter instead of radius. So divide 5.625 by 2. You get 2.8125.

Plug everything into the formula.

Pi*2.8125^2*7.5*1/3

(The ^2 means squared, or to the second power)

You get a number close to 20. Since we don’t know Pi, and we are not given a substitute for Pi, we make the answer in terms of Pi.

20 Cubic Inches^3.

Also, people who don’t know the answers to questions shouldn’t just put a random answer for the points. It’s unfair.


3 0
3 years ago
A population of 120,000 grows 3% per year for 15 years, how much will the population be after 15 years?
Wewaii [24]
270,000 is the answer because you have three over 100 so you do 100 divided by three which give you 0.15 then you do 120,000 times 0.15 to find out how much it grows per year to get 18,000 then you multiply 18’000 by 15 and get 270’000
3 0
3 years ago
Other questions:
  • Steve bought 2 plain pizzas and 1/4 of a pepperoni pizza.in all how much pizza did he buy
    10·2 answers
  • A circular picture is 8 inches in diameter.
    11·1 answer
  • For the 2015 Intel Science Fair, two brothers in high school recruited 47 of their classmates to take part in a two-stage study.
    5·1 answer
  • 2.85x10^6 / 30000 i need help with that
    5·1 answer
  • An airplane must clear a 60-foot pole at the end of a runway 500 yards long determine the angle of elevation at which the airpla
    6·1 answer
  • What is temperature of hot chocolate in degrees celsius?
    5·1 answer
  • Enter a value to balance the hanger
    6·1 answer
  • Solve. 7/3x+1/3x=4+5/3x The value of x is
    7·2 answers
  • PLZ HELP! I REALLY NEED HELP ON THIS! WILL GIVE BRAINLEIST!!! PLZZZDetermine any data values that are missing from the table, as
    9·1 answer
  • Given the matrix equation<br><br><br> AX + B = C
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!