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 98% confidence interval for the population mean life of the new model is _________.

A) 63.37 to 86.63
B) 61.60 to 88.41
C) 71.77 to 78.23
D) 71.28 to 78.72
E) 79.86 to 81.28