CA Foundation · Quantitative Aptitude · Statistical Description of Data
A data set has a smallest value of 12 and a largest value of 87. If it is to be grouped into classes of equal width 10, what is the minimum number of classes needed to cover all the values?
Eight classes are needed. The range is 87 minus 12, which is 75. Dividing by the class width of 10 gives 7.5, and since a fraction of a class cannot exist, the number is rounded up to 8 so that all observations are covered.
- A7
- B8Correct
- C9
- D10
Explanation
Range = 87 - 12 = 75. Number of classes = range / width = 75/10 = 7.5, which must be rounded up to 8 so that every value is covered. Choosing 7 would leave the largest values outside the classes.
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