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CA Foundation · Quantitative Aptitude · Statistical Description of Data

In a distribution with exclusive classes 20–30, 30–40, 40–50, 50–60, the frequencies are 8, 12, 20, 10. Using the idea of a frequency density per unit width, a new analyst merges the last two classes into 40–60. What is the frequency density (frequency per unit of class width) of the merged class?

The frequency density is 1.5. Merging 40–50 and 50–60 gives a frequency of 30 over a class width of 20, so density is 30 divided by 20, equal to 1.5. Dividing by the old width of 10 would wrongly give 3.

  1. A30
  2. B3
  3. C1.5Correct
  4. D0.5

Explanation

Merged frequency = 20 + 10 = 30. Width = 60 − 40 = 20. Density = 30/20 = 1.5. Option 3 divides by 10 (the old width), the wrong base; 30 is the frequency itself.

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