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

Multiple Choice

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