CA Foundation · Quantitative Aptitude · Statistical Description of Data
In a frequency distribution of marks, the class intervals are 0–10, 10–20, 20–30, 30–40 and 40–50, with frequencies 4, 9, 15, 12 and 5 respectively, using the exclusive method. How many students scored less than 30 marks?
28 students scored less than 30 marks. With the exclusive method, the upper limit of 20–30 is not included in that class, so the classes below 30 are 0–10, 10–20 and 20–30, giving 4 + 9 + 15 = 28 students.
- A15
- B28Correct
- C40
- D13
Explanation
Under the exclusive method, a mark of 30 belongs to the class 30–40, so students scoring below 30 are in the first three classes. Sum: 4 + 9 + 15 = 28. The value 13 comes from adding only the first two classes, which leaves out the 20–30 class.
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