Question

The total age of 23 boys and 32 girls is 573 years while that of 32 boys and 23 girls is 582 years. Find the average age of a boy and a girl respectively.

पर्याय

• 10, 11

• 12, 14

• 11, 10

• None of these

Answer 1

11, 10

Explanation:

Let average age of a boy = x and a girl = y

23x + 32y = 573

32x + 23y = 582

Here the coefficients of x and y are interchanged, in such cases a faster method of solving the equation is by adding and subtracting the equations.

Adding 55x + 55y = 1155

x + y = 21  .....(i)

Subtracting 9y – 9x = – 9

x – y = 1  ......(ii)

From (i) and (ii)

2x = 22, x = 11, y = 10