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WAEC Further Mathematics 2009 Question 38

Question 38

Probability

Three defective bulbs got mixed up with 7 good ones. If two bulbs are selected at random, what is the probability that both are good?

  1. A.3/7
  2. B.21/50
  3. C.7/15
  4. D.49/100
Show the answer and explanation

Answer: C (7/15)

Explanation

P = (7/10) × (6/9) = 42/90 = 7/15 (selection without replacement).