In a finance class the final grade is based on three tests H

In a finance class, the final grade is based on three tests. Historically, the instructor tells the class that the joint probability of scoring As on the first two tests is 0.5. A student assigns a probability of 0.7 that she will get an \"A\" on the first test. What is the probability that the student will score an A on the second test given that she scored an A on the first test?

0.17

0.67

0.71

0.95

Solution

Let A, B = getting A\'s on the first and second tests, respectively.

As

P(B|A) = P(A n B) / P(A)

then

P(B|A) = 0.5 / 0.7 = 0.71 [ANSWER, OPTION D]