Question

Mrs. Brown gives two tests to her class. 30% of the class passed both tests and 45% of the class passed the first test. What

percent passed the second test given that they passed the first test?
A)
15%
B)
33%
67%
D)
75%

Answer 1

C) 67%

Explanation:

Conditional probability:

P(A given B) = P(A and B) / P(B)

P(passed 2nd given passed 1st) = P(passed 2nd and 1st) / P(passed 1st)

P(passed 2nd given passed 1st) = 0.30 / 0.45

P(passed 2nd given passed 1st) = 0.67