CA Foundation · Quantitative Aptitude · Probability
Three events A, B and C are mutually exclusive and exhaustive. P(A) = 2P(B) and P(C) = 3P(B). What is the probability that A or C occurs?
The probability is 5/6. Letting P(B) = x, the total of x + 2x + 3x must equal 1, so x = 1/6. A and C are mutually exclusive, so their probabilities simply add: 2/6 + 3/6 = 5/6.
- A5/6Correct
- B1/6
- C2/3
- D1/2
Explanation
Let P(B) = x. Then x + 2x + 3x = 1, so x = 1/6. P(A) = 2/6 and P(C) = 3/6. Since A and C are mutually exclusive, P(A or C) = 2/6 + 3/6 = 5/6. Option 1/6 is only P(B).
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