# RS Aggarwal Solutions Class 9 Mathematics Solutions for Mean Median And Mode Of Ungrouped Data Exercise 18B in Chapter 18 - Mean Median And Mode Of Ungrouped Data

Question 4 Mean Median And Mode Of Ungrouped Data Exercise 18B

The following data give the number of boys of a particular age in a class of 40 students.

Age (in years) Frequency (fi)
15 3
16 8
17 9
18 11
19 6
20 3

Calculate the mean age of the students.

Age (in years) (xi) Frequency (fi) fi xi
15 3 45
16 8 128
17 9 153
18 11 198
19 6 114
20 3 60
Σ fi = 40 Σ fi xi = 698

We know that

Mean age of the students = Σ fi xi/ Σ fi

By substituting the values

Mean age of the students = 698/40 = 17.45 years

Therefore, the mean age of the students is 17.45 years.

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