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WAEC Mathematics 2017 Question 32

Question 32

Probability

In a class of 45 students, 28 offer chemistry and 25 offer Biology. If each student offers at least one of the two subjects, calculate the probability that a student selected at random from the class offers Chemistry only.

  1. A.2/9
  2. B.4/9
  3. C.5/9
  4. D.7/9
Show the answer and explanation

Answer: B (4/9)

Explanation

Both = 28 + 25 − 45 = 8, so Chemistry only = 20. Probability = 20/45 = 4/9.