# Using Z-Scores to Solve a Problem

Assume that replacement time for TVs are normally distributed with a mean of 8.2 years and a standard deviation of 1.1 years. The probability a randomly selected TV will have replacement time less than 5.5 years to be .0071.

Determine the time length of a warranty such that only 3.5% of the TVs would be replaced before the warranty expires.

Thank you.

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#### Solution Preview

This problem is sort of the opposite of the problems that gives you a raw score x and want you to find the associated probability.

Here, we have the probability and need to find x. We want ...

#### Solution Summary

The solution explains how to use z-scores to answer the question.

$2.19