A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.

Number of days

0-6

6-10

10-14

14-20

20-28

28-38

38-40

Number of students

11

10

7

4

4

3

1

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Solution

Here, we have

sum from blank to blank of f subscript i equals 40 space and italic space italic sum from blank to blank of f subscript i x subscript i italic equals italic 499

Now,

top enclose straight x equals fraction numerator begin display style sum from blank to blank of end style f subscript i x subscript i over denominator begin display style sum from blank to blank of end style f subscript i end fraction equals 499 over 40 equals 12.47

Hence, the mean number of days a student was absent is 12.48.

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