Hi there, Not sure if this is the right place, but the problem states that a battery has a population mean of 40 hours and standard deviation of 5. Let X represent the mean lifetime of batteries in a simple random sample size of 100. What is P(X <= 36.7)? I tried computing this with X~N(40, 0.25) according to the CLT, but when I tried calculating z = (36.2 - 40)/√(0.25), the z-score was 7.6 and way too far from the z-score table. Any ideas?? Thanks!