Question

The mean of marks of 50 students in a class is 58. The mean marks of boys is 55 and girls is 60. Find the number of boys and girls.(B means" boy" & G means "girls") ​

Answer 1

ANSWER

Total students in class =150

mean weight=60kg

total weight =150×60=9000kg

Let the total number of boys =x

mean weight of boys =70kg

total weight of boys =70×x=70xkg

total number of girls = total students - no. of boys =150−x

mean weight of girls=55kg

total weight of girls =55×(150−x)=55×150−55x=(8250−55x)kg

Total weight = weight of boys + weight of girls

9000=70x+(8250−55x)

9000=70x+8250−55x

9000−8250=70x−55x

750=15x

x=

15

750

x=50

So number of boys =50

number of girls =150−50=100