# The average score of boys in an examination of a school is 71 and that of girls is 73. The average score if school in examination 71.8. Find the ratio if number of boys to the number of girls that appeared in examination.

2
by sofiya

2015-02-01T15:34:23+05:30

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Let the number of boys = x
number of girls = y
we need to find .

The average score of boys in the examination is 71
total score of boys = 71
× x = 71x
The average score of girls in the examination is 73
total score of girls = 73
× y = 73y
So total mark of school = 71x + 73y     ---------------(1)

average score if school in examination 71.8
so total mark = 71.8
× (x+y)             -----------------(2)

From equations (1) and (2);

71x + 73y = 71.8(x+y)
⇒ 71x + 73y = 71.8x + 71.8y
⇒ 73y - 71.8y = 71.8x - 71x
⇒ 1.2y = 0.8x
⇒0.8x = 1.2y

Ratio of boys and girls is 3:2.
2015-02-01T15:38:20+05:30
The ratio of number of boys to that of girls appeared in the examination is 3:2.