**Note: Question 4.56 is provided before hand, but I am only trying to answer 4.57.

Attempting to figure out the most efficient way to answer this question in STATA. I know how to do it by hand but am having a hard time doing this in STATA.

A study considered risk factors for HIV infection among intravenous drug users [11].It found that 40% of users who had = 100 injections per month (light users) and 55% of users who had > 100 injections per month (heavy users) were HIV positive.

4.56** Suppose we have a group of 10 light users and 10 heavy users.What is the probability that exactly 3 of the 20 users are HIV Positive?

4.57 What is the probability that at least 4 of the 20 users are HIV positive?