Life tests performed on a sample of 13 batteries of a new model indicated: (1)an average life of 75 months, and (2)a standard deviation of 5 months.Other battery models, produced by similar processes, have normally distributed life spans.The 90% confidence interval for the population mean life of the new model is _________.
A)66.78 to 83.23
B)72.72 to 77.28
C)72.53 to 77.47
D)66.09 to 83.91
E)73.34 to 76.25

Question

Quizplus · Accepted Answer

The 90% confidence interval is calculated using the sample mean, standard deviation, and the t-distribution for a sample size of 13.

Life Tests Performed on a Sample of 13 Batteries of a New