CMA Foundation · Fundamentals of Business Mathematics and Statistics · Statistical Representation of Data
The marks of students in a test range from a lowest value of 12 to a highest value of 87. A statistician wants to group them into 5 classes of equal width. What is the minimum whole-number class width she should use?
The minimum whole-number class width is 15. The range is 87 minus 12, which equals 75, and dividing by 5 classes gives exactly 15. A width of 14 would cover only 70 units and fail to include all observations.
- A14
- B15Correct
- C16
- D17
Explanation
Range = 87 − 12 = 75. Width = range ÷ number of classes = 75 ÷ 5 = 15, which is already a whole number and covers all data. Using 14 would give 5 × 14 = 70, which is less than 75 and would leave some values out.
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