According to a survey if American households the probability

According to a survey if American households, the probability that the residents own 2 cars if annual household income is over $80,00 is 85%. Of the households surveyed, 65% had incomes over $80,000 and 75% had 2 cars. The probability that the residents of a household own 2 cars and have an income over $80,000 a year is:
a. 0.60
b. 0.55
c. 0.67
d. 0.85

Solution

Let

C = has 2 cars
I = income is over 80000

Here,

P(C|I) = 0.85

P(I) = 0.65

P(C) = 0.75

Thus,

P(C n I) = P(I) P(C|I) = 0.85*0.65

= 0.5525

= 0.55 [ANSWER, B]