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When 5 children from class A join class B, the number of children in both classes is the same. If 25 children from B, join A, then the number of children in A becomes double the number of children in B. The ratio of the number of children in A to those in B is:

When 5 children from class A join class B, the number of children in both classes is the same. If 25 children from B, join A, then the number of children in A becomes double the number of children in B. The ratio of the number of children in A to those in B is: Correct Answer 19 : 17

Given:

When 5 children join B from A, the number of children in both classes is the same

If 25 children from B join A, the number of children in A becomes double the number in B

Calculation:

Let the number of children in class A be 'a' and that of class B be 'b'

As per question

5 children from class A join class B

⇒ a - 5 = b + 5

⇒ a - b = 10          -----(1)

Also, when 25 children from B join A, the number of children in A becomes double the number of children in B

⇒ a + 25 = 2 × (b - 25)

⇒ 2b - a = 75         -----(2)

By adding equations (1) and (2), we get

b = 85 and 

a= 95

∴ The ratio of the number of children in A to the number of children in B is 19 ∶ 17 

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