Question

There are three sections a,b and c in a class. the ratio of students in sections in a and b is 2:3 and that b and c is 4:5. if the total number of students in the class be 210, how many students are there in section b

Answer 1

72 students

Explanation:

A:B = 2:3

B:C = 4:5

In order to find B, we must first connect the ratios.
Since both the ratios have B in common, we can join the ratios together by changing B into the same number in both ratios.

B in the first ratio = 3

B in the second ratio = 4

In order to make the value of B the same in both ratios, we can multiply 3 x 4.
This means the ratio A:B should be multiplied by 4 while B:C is multiplied by 3.

4 x (2:3) = 8:12

3 x (4:5) = 12:15

Since the value of B is now the same in both ratios, we can write the ratio in the form A:B:C.

A:B:C = 8:12:15

8 + 12 + 15 = 35

210 must be divided into 35 parts

210 ÷ 35 = 6

The number of student in section B would be the ratio of B multiplied by one part.

12 x 6 = 72