There are 1000 juniors in a college Among the 1000 juniors 2

There are 1000 juniors in a college. Among the 1000 juniors, 200 students are taking STAT200, and 100 students are taking PSYC300. There are 50 students taking both courses. (show work)

a. What is the probability that a randomly selected junior is taking at least one of these two courses?                                                                                                      

b. What is the probability that a randomly selected junior is taking PSYC300, given that he/she is taking STAT200?

Solution

Probability (at least one of the two cources) = 200/1000 + 100/1000 -50/1000 = 250/1000 = 1/4 (ans) or 0.25 (ans)

P( taking PSYC300, given that he/she is taking STAT200) = P (both subject)/ P(stat 200) =50/1000*1000/200 = 1/4 (ans) or 0.25 (ans)