You Want to Estimate the Average Useful Life of the Lithium

Multiple Choice

You want to estimate the average useful life of the lithium cell phone batteries that your company has just put on the market.You take a random sample of 25 batteries to be tested.The test reveals a sample average life of 1560 hours.The sample standard deviation is 68 hours.Assume that the population distribution is approximately normal.Construct a 95% confidence interval estimate of average useful life for the full population of lithium cell phone batteries produced by your company.Report the upper bound for your interval.

A) 1588.07
B) 1425.82
C) 1377.21
D) 1522.13
E) 1487.65