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WAEC Further Mathematics 2010 Question 21

Question 21

Statistics

The mean age of 15 pupils in a class is 14.2 years. One new pupil joined the class and the mean changed to 14.1 years. Calculate the age of the new pupil.

  1. A.12.4 years
  2. B.12.6 years
  3. C.13.2 years
  4. D.14.1 years
Show the answer and explanation

Answer: B (12.6 years)

Explanation

Total age of 15 pupils = 15 × 14.2 = 213. New total = 16 × 14.1 = 225.6. The new pupil is 225.6 − 213 = 12.6 years old.