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Suppose that A and B are two independent events with P(A)=0.2 and P(B)=0.4. P(A

ID: 3374909 • Letter: S

Question

Suppose that A and B are two independent events with P(A)=0.2 and P(B)=0.4. P(A or B) is

There is a 0.20 chance that a college student will go to a graduate school. If s|he goes to a graduate school with probability 0.7, s|he will have the life style that s|he wants. If s|he does not go to a graduate school, her|his chance is 0.4.

The probability tree that describes this problem is

A

B

C

D

Event A occurs with probability 0.8. The probability that event B occurs given that A occurs is 0.5. The probability that both A and B occur is

0.08

Explanation / Answer

since A and B are two independent events

P(A and B)=P(A)*P(B)

P(A or B)=P(A)+P(B)-P(A).P(B)

=0.2+0.4-0.2*0.4

=0.52

ANSWER:0.52

Solution2:

P(A)=0.8

P(B/A)=0.5

P(A and B)=P(B//A)*P(A)--- by definition of conditional probability

=0.5*0.8

=0.4

The probability that both A and B occur is 0.4