Life of Smoke Detectors The average lifetime of smoke detectors that a company manufactures is 5 years, or 60 months, and the standard deviation is 9 months. Find the probability that a random sample of 31 smoke detectors will have a mean lifetime between 57 and 62 months. Assume that the sample is taken from a large population and the correction factor can be ignored. Round the final answer to at least four decimal places and intermediate z-value calculations to two decimal places.

Big Ideas Math A Bridge To Success Algebra 1: Student Edition 2015
1st Edition
ISBN:9781680331141
Author:HOUGHTON MIFFLIN HARCOURT
Publisher:HOUGHTON MIFFLIN HARCOURT
Chapter9: Solving Quadratic Functions
Section: Chapter Questions
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Life of Smoke Detectors The average lifetime of smoke detectors that a company manufactures is 5 years, or 60 months, and the standard deviation is 9 months. Find the probability that a random sample of 31 smoke detectors will have a mean lifetime between 57 and 62 months. Assume that the sample is taken from a large population and the correction factor can be ignored. Round the final answer to at least four decimal places and intermediate z-value calculations to two decimal places.
P(57<the mean < 62)= 

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