A drug trial is testing the effectiveness of two drugs. If 50 patients are given Drug A, 20 patients are given Drug B, and 100 patients are given a placebo, what is the probability that a patient will NOT be given a placebo?
There are 70 people who are given either drug A or B, and 100 who are given the placebo. This makes the total number of patients 170, 70 of which don't receive the placebo. You then divide 70 by the 170, getting the 41%
