Question

The ratio of boys to girls in a class is 5:7. There are 36 students in the class. How many students are girls?

Answer 1

Answer:

5:7=36

Step-by-step explanation:

5x+7x=36

12x=36

x=36/12

x=3

here 7 is the ratio of girl so,

7x=7×3

21,the total number of girls in class

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Answer 2

Let the number of boys be = x

Then , Number of girls = ( 36 - x )

since total number of students = 36

Now, According to the question,

$\frac{x}{36 - x} = \frac{5}{7} \\ \\ = > \: 7x = 5(36 - x) \\ \\ = > \: 7x = 180 - 5x \\ \\ \: = > 7x + 5x = 180 \\ \\ = > 12x = 180 \\ \\ = > x = 15$

Therefore, Number of girls

$= 36 - 15 = 21$

No. Of boys = 15 , No. of Girls = 21

Shortcut :

Add up the ratio i.e. 5+7 = 12

Now , Number of boys

$= \frac{5}{12} \times 36 \\ = 5 \times3 \\ = 3$

Number of girls :

$= \frac{7}{12} \times 36 \\ = 7 \times 3 \\ = 21$

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