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JAMB Mathematics 1990 Question 47

Question 47

Measures of Central Tendency

The mean of 10 positive numbers is 16. When another number is added, the mean becomes 18. Find the eleventh number

  1. A.3
  2. B.16
  3. C.18
  4. D.38
Show the answer and explanation

Answer: D (38)

Explanation

The first 10 numbers add up to 160. The 11 numbers add up to 11 × 18 = 198, so the new number is 198 − 160 = 38.