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CA Foundation · Quantitative Aptitude · Statistical Description of Data

A distribution of 100 observations has class intervals 0–20, 20–40, 40–60, 60–80, 80–100. The relative frequencies are 0.10, 0.25, 0.30, 0.20 and 0.15 respectively. Using the 'more than' cumulative frequency approach, how many observations are 40 or more?

Sixty-five observations are 40 or more. Add the relative frequencies of the classes from 40 upward, 0.30, 0.20 and 0.15, to get 0.65, then multiply by the total of 100. The figure 35 is the count below 40, the complementary less than value.

  1. A35
  2. B65Correct
  3. C75
  4. D40

Explanation

Observations at 40 or more fall in classes 40–60, 60–80 and 80–100. Their relative frequencies sum to 0.30 + 0.20 + 0.15 = 0.65. Multiplying by 100 gives 65. Option 35 is the number below 40 (0.10+0.25), which is the 'less than' count.

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