Question

A quality control expert at LIFE batteries wants to test their new batteries. The design engineer claims they have a standard deviation of 54 minutes with a mean life of 828 minutes. If the claim is true, in a sample of 107 batteries, what is the probability that the mean battery life would be greater than 821.9 minutes? Round your answer to four decimal places.

Answer 1

$\mu _{x}=\mu =828$ and

54 ア=-=5.22 Vn V107

821.9-828-6.1 5.22 ー-/4 z = 5.22

PT> 821.9)-P(Z >-1.17) = 0.8791