Frank has a 65% chance of receiving an A grade in geology, a 60% chance of receiving an A grade in mathematics, and a 77% chance of receiving an A grade in geology or mathematics (or both). Find the probability that he receives A grades in both geology and mathematics.
P(geo and math) = P(geo) + P(math) - P(geo or math)
= 0.65 + 0.60 - 0.77
= 1.25 - 0.77
= 0.48
1 answer