Question 20.

Let the original number of students be 'n' whose average weight is 'x'

Let the number of students added be 'm' and the average weight will be x + 3

We need to find the value of n : m

It is given, average weight of students in a class increased by 0.6 after new students are added.

Therefore,

$\frac{nx + m(x + 3)}{n + m} = x + 0.6$

$nx + mx + 3m = mx + nx + 0.6n + 0.6m$

$2.4m = 0.6n$

$4m = n$

$\frac{n}{m} = \frac{4}{1}$