Question

The mean weight of 200 students in a school is 56 kg . The mean weight of the boys is 65 kg while that of the girls is 50 kg . Find the number of boys and that of the girls in the school .

Answer 1

Here is your answer:-

Let the number of boys be x.

Let the number of girls be y.

So:

x + y = 200..................................(1)

Mean weight of x boys is 65

Weight of x boys = 65 x

Mean weight of y boys is 50

Weight of y girls is 50 y

Now weight of x boys + weight of y girls is the total weight

65 x + 50 y = Total weight

Mean weight of 200 students is 56

==> Total weight / 200 =56

==> Total weight = 56 * 200

==> 11200

Hence:

65 x + 50 y = 11200

==> 13 x + 10 y = 2240........................(2)

Multiplying (1) with 10 we get:

==> 10 x + 10 y = 2000......................(3)

Subtracting (3) from (2) we get:-

==> 3 x = 240

==> x = 240 / 3

==> x = 80

But x + y = 200 ..............(From 1)

==> 80 + y =200

==> y = 200 - 80

==> y = 120

The number of girls was 120 and number of boys was 80

Hope it helps you

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Answer 2

HOPE THIS WILL BE HELP YOU...