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

The marks of 60 students are grouped into classes 10-20, 20-30, 30-40, 40-50 and 50-60. The highest mark is 58 and the lowest mark is 12. Using the exclusive method, what is the class width if the data are grouped into 5 classes with equal width starting at 10?

The class width is 10, because the classes run from 10 to 60, a span of 50, and dividing this by the 5 equal classes gives 10. The actual data range of 46 is not used since the class limits are already fixed.

  1. A8
  2. B10Correct
  3. C12
  4. D5

Explanation

Range of the classes is 60 - 10 = 50. Dividing by 5 classes gives a width of 50/5 = 10. Option 8 comes from using the range of the data (58 - 12 = 46) divided by 5 and rounding, which ignores the stated starting point of 10.

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