Suppose that battery lifetimes are known be normally distributed with mean of years and standard deviation 15 months. If a random sample of size 12 is taken from this population, then what (if anything) can be said about the distribution of average lifetimes (in months)? Hint: Understand why this is sampling distribution problem and the implications of n 30 on the sampling distribution. The distribution of average lifetimes (in months) is approximately Normal (u = 30, 0 = 15/ n ) for any value of n. The distribution of average lifetimes (in months) is exactly Normal (u = 30, 0 = 15 ) for any value of n. The distribution of average lifetimes (in months) is exactly Normal (u = 30, 0 = 15/ n) when n 2 30 by Central Limit Theorem. The distribution of average lifetimes (in months) is approximately Normal (u = 30, 0 = 15 ) when n 2 30 by Central Limit Theorem