Question

Suppose A and B are independent events. The probability that event A will not occur is 0.1 and the probability that event B will occur is 0.7. Find P(A), P(not B) and P(A and B).

Answer 1

Answers:

• P(A) = 0.9
• P(not B) = 0.3
• P(A and B) = 0.63

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Work Shown:

P(A) = 1 - P(not A)

P(A) = 1 - 0.1

P(A) = 0.9

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P(not B) = 1 - P(B)

P(not B) = 1 -0.7

P(not B) = 0.3

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P(A and B) = P(A)*P(B) only when A and B are independent

P(A and B) = 0.9*0.7

P(A and B) = 0.63

Answer 2

The probability for A is 1-0.1 is 90%

P(A)=90%

P(NOT B)=30%

P(A AND B)=0.9+0.7/2=1.6/2=80%

p(a and b) may be a little off.