Question

A laptop manufacturer has completed extensive testing over a long time and claims that their new computer batteries will last for 4 hours with a std. dev. of 0.2 hours, that the data is normally distributed, and lists this on their spec. sheet. One of their engineering interns took a recent sample of data claims that the mean is greater than that claimed on the spec. sheet based on a single same with n-50, mean -4.05 hours for alpha 0.05 If the null hypothesis is that the specifications on the spec. sheet are valid, determine the appropriate reject criteria Zo less than-1.645 Zo greater than 1.645 Zo less than -1.96 or greater than 196 Zo greater than 1.678

The answer is NOT "To greater than 1.678"

Answer 1

Population standard deviation is known so use Z test.

Z critical value at 0.05 level = 1.645

Critical criteria : Zo greater than 1.645