Ok, the question says Binomial with n=40. p=0.6 use normal approximation and determine.. a) value at 14. b)value lest then 12. So I thought I had this down and packed but the answer in the back of the book tells me otherwise. Anyways the following is my working. Y~Nor(13.5<x<14.5) Mean=np=24 S.D = sqrt(np(1-p)) = 3.094 larger prob area Z=(x-mean)/S.D =(14.5 - 24)/3.094 =-3.07 (Tables book, 3.07 = 0.9989) So (1-0.9989) smaller prob area Z=(x-mean)/S.D =(13.5 - 24)/3.094 =-3.39 (Tables book, 3.39 = 0.9997) So (1-0.9997) So the final answer is: larger prob area - smaller prob area total prob =(1-0.9989) - (1-0.9997) =8*10^-4 But the actual answer is meant to be 0.049? B) I do pretty much the same thing But after the whole Z=(x-mean)/S.D (x=11.5) end up with Z=-4.034 Which isnt on the tables book. So I cant figgure out the final prob. Thanks!