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WAEC Further Mathematics 2023 Question 31

Question 31

Probability

If X and Y are two independent events such that P(X) = 1/8 and P(X ∪ Y) = 5/8, find P(Y).

  1. A.4/7
  2. B.3/7
  3. C.4/21
  4. D.1/6
Show the answer and explanation

Answer: A (4/7)

Explanation

For independent events P(X ∪ Y) = P(X) + P(Y) − P(X)P(Y): 5/8 = 1/8 + (7/8)P(Y), so P(Y) = 4/7.