1. A search engine site claims that, on average, one out of five visitors clicks on an ad.
(a) If 8 users visit the site, what is the probability that at least three click on an ad?
(b) If 8 users visit the site, what is the probability that less than two of them click on an ad?
(c) If 800 users visit the site, would the probability that less than 200 click on an ad be higher or lower than the answer found in part (b)? Write a few sentences explaining your answer- computations are not required (or desired)
(d) Suppose 90 users visit the site during a particular minute, use the normal approximation to estimate the probability that more than 25 of them click on an ad.
(e) If 900 users visited the site, would the probability that more than 250 of them click on an ad be higher or lower than the answer found in part (d)? Write a few sentences explaining your answer- computations are not required (or desired)
2. Suppose that, overall, 5% of all tax returns are audited by the IRS.
(a) If an accountant has 7 clients for whom she prepared tax returns, what is the probability that less than 3 will be audited?
(b) If the accountant has 30 clients, what is the probability that at least one is audited?
(c) Suppose the accountant prepares 500 returns, use the normal approximation to estimate the probability that more than 20 of the returns are audited.