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JAMB Mathematics 1995 Question 45

Question 45

Measures of Dispersion

Class: 1-3, 4-6, 7-9
Frequency: 5, 8, 5
Find the standard deviation of the data using the table above.

  1. A.5
  2. B.√6
  3. C.5/3
  4. D.√5
Show the answer and explanation

Answer: D (√5)

Explanation

Use the class mid-points 2, 5, 8. The mean is 5. Σf(x − 5)² = 5(9) + 8(0) + 5(9) = 90, and 90/18 = 5 is the variance, so the standard deviation is √5.