problem-6.4

problem-6.4  The exponential distribution is skewed. It takes a larger sample than for a non-skewed distribution for the sampling distribution of \Xbar to become approximately normal. The size is somewhere in the 25 to 50 range. Verify with
> res = c();for(i in 1:500) res[i] = mean(rexp(25,1));qqnorm(res)