The service life in kilometer of Goody tires is assumed to follow a normal distribution with a standard deviation of 5,000 km. A random sample of 25 tires yielded a mean service life of 30,000 km.  1.Find the 95% confidence interval for the true mean service life. 2. Find a 75% confidence interval for the true mean service life. 3. Calculate the widths of the intervals found in 1 and 2. How do these widths change as the confidence level decreases?

A First Course in Probability (10th Edition)
10th Edition
ISBN:9780134753119
Author:Sheldon Ross
Publisher:Sheldon Ross
Chapter1: Combinatorial Analysis
Section: Chapter Questions
Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...
icon
Related questions
Topic Video
Question

The service life in kilometer of Goody tires is assumed to follow a normal distribution with a standard deviation
of 5,000 km. A random sample of 25 tires yielded a mean service life of 30,000 km. 

1.Find the 95% confidence interval for the true mean service life.

2. Find a 75% confidence interval for the true mean service life.

3. Calculate the widths of the intervals found in 1 and 2. How do these widths change as the
confidence level decreases?

Expert Solution
steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Knowledge Booster
Hypothesis Tests and Confidence Intervals for Means
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, probability and related others by exploring similar questions and additional content below.
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
A First Course in Probability (10th Edition)
A First Course in Probability (10th Edition)
Probability
ISBN:
9780134753119
Author:
Sheldon Ross
Publisher:
PEARSON
A First Course in Probability
A First Course in Probability
Probability
ISBN:
9780321794772
Author:
Sheldon Ross
Publisher:
PEARSON