A survey of U.S. adults found that 39% of those who have online accounts use the same or very similar passwords for many of their accounts. You randomly select 500 U.S. adults who have online accounts. Find the probability that the number who use the same or very similar passwords for many of their accounts is 

(a) Exactly 175, 

(b) No more than 225, and 

(c) At most 200.

A binomial experiment is given. Determine whether you can use a normal distribution to approximate the binomial distribution. If you can, find the mean and standard deviation. If you cannot, explain why.