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WAEC Further Mathematics 2015 Question 35

Question 35

Statistics

In calculating the mean of 8 numbers, a boy mistakenly used 17 instead of 25 as one of the numbers. If he obtained 20 as the mean, find the correct mean.

  1. A.24
  2. B.23
  3. C.21
  4. D.19
Show the answer and explanation

Answer: C (21)

Explanation

Wrong total 160; correct total 160 − 17 + 25 = 168, mean 168/8 = 21.