Question

The mean weight of females in a class is 60kg and that of the males is 72kg. If the mean weight of the class is 68kg, what is the ratio of females to males in the class?

Answer 1

Answer:

2:1

let x be no. of boy and y be no. of girls

68= (60x+ 72y)/(x+y)

68x+ 68y= 60x+ 72y

8x= 4y

y/x= 2

Answer 2

Answer:

The ratio of females to males in the class is $1:2$

Step-by-step explanation:

Let the number of females and males in the class be f and m respectively.

Mean weight of females $=\frac{ sum of weights of females}{number of females}$

$60 = \frac{(sum of weights of females)}{f}$

Therefore, sum of weights of females $= 60f$

Mean weight of males $= \frac{sum of weights of males}{no of males}$

$72 = \frac{(sum of weights of males)}{m}$

Therefore, sum of weights of males $= 72f$

$68 = \frac{(sum of weights of males and females)}{(f+m)}$

$68 = \frac{(60f+72m) }{(f+m)}$

$68f + 68m = 60f + 72m$

$8f = 4m$

$f/m = 1/2$

Hence, the ration of females to males in the class is $1:2.$