Quandaries
and Queries 

Barb secondary (1012) student The question is this one: 

Hi Barb, Use the normal distribution to find the probability that a single TV set would have a replacement time of greater than 10.0 years.
which is approximately 0.05. Now you have a binomial problem. You have a random sample of n = 250 TV sets, "success" is a TV set with replacement time of greater than 10.0 years, so p = 0.05 and you want the probability of at least 15 successes. Since n is large you should use the normal approximation to the binomial. Thus the number of successes X has, approximately, a normal distribution with mean np = 250 0.05 = 12.5 and variance np(1p) and you want the probability that X is larger than 15. Can you see how to complete the problem now? Andrei and Penny 

