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A research engineer for a tire manufacturer is
Chapter 8, Problem 29E(choose chapter or problem)
Problem 29E
A research engineer for a tire manufacturer is investigating tire life for a new rubber compound and has built 16 tires and tested them to end-of-life in a road test. The sample mean and standard deviation are 60,139.7 and 3645.94 kilometers. Find a 95% confidence interval on mean tire life.
Questions & Answers
QUESTION:
Problem 29E
A research engineer for a tire manufacturer is investigating tire life for a new rubber compound and has built 16 tires and tested them to end-of-life in a road test. The sample mean and standard deviation are 60,139.7 and 3645.94 kilometers. Find a 95% confidence interval on mean tire life.
ANSWER:
Step 1 of 2
Given,
Sample size, n = 16.
The sample mean,
The standard deviation,
For and s, the mean and standard deviation of a random sample from a normal distribution with unknown variance , a Confidence Interval on is given by,
where is the upper percentage point of the t distribution with n – 1 degrees of freedom