Question

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 0.9 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

Answer 1

0.5556 or 55.56%

Explanation:

If the probability of getting an A in both tests, P(B), is 0.5, and the probability of getting an A in the first test, P(F), is 0.9, then the probability of getting an A on the second test, P(S) is:

`P(B) = P(F)*P(S)\\0.5=0.9* P(S)\\P(S) = 0.5556=55.56\%`

Given that a student has scored an A on the first test, the probability that the student will score an A on the second test is 0.5556 or 55.56%