Question

The mean weight of 60 students in a class is 40 kg. The mean weight of boys is 50 kg while that of girls is 30 kgfind the number of boys and girls

Answer 1

Answer:

The number of boys = 30

The number of girls = 30

Step-by-step explanation:

It is given that,

• The mean weight of 60 students in a class is 40 kg.

Therefore total weight = 60 x 40= 240

Let N be the number of boys, then

number of girls = 60 - N

• The mean weight of boys is 50 kg

Total weight of boys = 50N

• The mean weight of girls is 30

Total weight of boys = 30(60 -N)

To find N

50N + 30(60 -N) = 2400

20N = 600

N= 30

The number of boys = 30

The number of girls = 60 - 30 = 30

Answer 2

Answer:

There are 30 boys and 30 girls

Step-by-step explanation:

Total number of students = 60

Define x:

Let the number of girls be x

Number of boys = (60 - x)

Find the total weight of the class:

Average = 40 kg

Sum = 40 x 60 = 2400 kg

Find the weight of the boys:

Average = 50 kg

Sum = 50(60 - x) = (3000 - 50x) kg

Find the weight of the girls:

Average = 30 kg

Sum = 30x kg

Solve x:

3000 - 50x  + 30x = 2400

3000 - 20x = 2400

20x = 600

x = 30

Find the number of boys and girls:

Girls = x = 30

Boys = 60 - x = 60 - 30 = 30

Answer: There are 30 boys and 30 girls