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JAMB Mathematics 1994 Question 45

Question 45

Measures of Central Tendency

The mean of twelve positive numbers is 3. When another number is added, the mean becomes 5. Find the thirteenth number.

  1. A.29
  2. B.26
  3. C.25
  4. D.24
Show the answer and explanation

Answer: A (29)

Explanation

The twelve numbers total 36. Thirteen numbers with mean 5 total 65, so the new number is 65 − 36 = 29.