CMA Foundation · Fundamentals of Business Mathematics and Statistics · Statistical Representation of Data
A frequency distribution of daily sales (in ₹ thousand) uses inclusive classes: 10-19, 20-29, 30-39, 40-49. What is the class width (class interval) after converting to the exclusive form with true class limits?
The class width is 10. Converting the inclusive classes to true limits means subtracting 0.5 from each lower limit and adding 0.5 to each upper limit, so 10-19 becomes 9.5-19.5, whose width is 10. The stated difference 19-10 equals 9 and is misleading.
- A9
- B10Correct
- C11
- D8
Explanation
The gap between the upper limit 19 and next lower limit 20 is 1, so the correction is 0.5. True limits of the first class are 9.5-19.5, giving width 19.5 - 9.5 = 10. Choosing 9 uses the difference of stated limits, which ignores the correction.
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