The total of 72 students took two courses. The table below shows the number of students in two courses according to their final grades.

Question

A B C D F

CALCULUS 10 7 8 5 6

STATISTICS 12 6 6 8 4

A student is selected random. Find the following probabilities:

a) the student took calculus

b) the students took statistics and got B

c) the student took calculus and got A

d) given that the student took calculus, what is the probability that he/she got F?

e) If we select 2 students at random ( without replacement ), what is the probability that both took calculus?

Answer 1

36 = half the students took calculus, p = 36/72 = 0.50

6 students took statistics and got a B, p = 6/72 = 0.083

10 students took calculus and got an A, p = 10/72 = 0.14

6 of the 36 who took calculus got an F, p = 6/36 = 0.17

Without replacement (36/72)(35/71) = probability both took calculus. p = 0.246