A Laptop Battery Lifespan Follows a Normal Distribution with Mean $\sigma$

Multiple Choice

A laptop battery lifespan follows a normal distribution with mean μ = 22 months and a standard deviation $\sigma$ = 6 months.To test the alternative hypothesis that μ < 22 with α = .05, 36 laptop batteries are randomly selected.Assuming that μ = 21, the probability of type II error is approximately ________.

A) -0.65
B) 0.2422
C) 0.64
D) 0.7422
E) 0.2508