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CMA Foundation · Fundamentals of Business Mathematics and Statistics · Statistical Representation of Data

A frequency distribution of daily sales (in ₹ thousand) of a Pune store has classes 10-20, 20-30, 30-40, 40-50 with frequencies 6, 14, 18, 12. When drawing a frequency polygon by the mid-point method, which pair of points would be plotted for the first two classes?

The points are (15, 6) and (25, 14). A frequency polygon is drawn by plotting each class mid-point against its frequency, so 10-20 gives 15 and 20-30 gives 25, joined by straight lines. Class limits are not used as the x-values.

  1. A(15, 6) and (25, 14)Correct
  2. B(10, 6) and (20, 14)
  3. C(20, 6) and (30, 14)
  4. D(15, 14) and (25, 6)

Explanation

The frequency polygon plots class mid-points against frequencies. Mid-point of 10-20 is (10+20)/2 = 15 with frequency 6, and of 20-30 is 25 with frequency 14. Using lower limits or upper limits (options 2 and 3) is wrong because the polygon uses mid-values.

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