Question

40% of the class consists of boys, what is the ratio between boys and

girls?​

Answer 1

Given,

Boys percentage in the classroom = 40%

To find,

The ratio of boys and girls in that classroom.

Solution,

We will assume, that the total number of students of that classroom is denoted by 100%, for the sake of an easier calculation.

The percentage of girls :

= Total percentage - Percentage of boys

= 100% - 40%

= 60%

The ratio of boys and girls :

= 40% : 60%

= 40 : 60

= 4:6

= 2:3

(This cannot be further simplified, so we will assume it as the final ratio of boys and girls.)

Hence, the ratio of boys and girls will be 2:3.

Answer 2

$Let \: Total \: strength \: of \: a \:class = 100$

$i) Number \: of \: boys \: in \: the \: class \\= 40\%\: of \: Total \: strength \\= \frac{40}{100} \times 100 \\= 40$

$ii) Number \: of \: girls \: in \: the \: class \\= 60\%\: of \: Total \: strength \\= \frac{60}{100} \times 100 \\= 60$

$\red{ Ratio \: between \: boys \: and \: girls }$

$= 40 : 60$

$= \frac{40}{60} \\= \frac{\cancel {20}\times 2 }{\cancel {20}\times 3 }\\= \frac{2}{3}\\ \green { = 2 : 3 }$

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