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

Question 30 Mean Median And Mode Of Ungrouped Data Exercise 18A

The mean marks (out of 100) of boys and girls in an examination are 70 and 73 respectively. If the mean

marks of all the students in that examination is 71, find the ratio of the number of boys to the number of

girls.

Answer:

Consider x: 1 as the ratio of number of boys to the number of girls

So we get

Sum of marks of boys = 70x

Sum of marks of girls = 73 (1) = 73

We know that

Sum of marks of boys and girls = 71 (x + 1)

It can be written as

70x + 73 = 71 (x + 1)

On further calculation

7x + 73 = 71x + 71

So we get

x = 2

Therefore, the ratio of the number of boys to the number of girls is 2: 1.

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