CAT 2022 Slot 1 QA Question & Solution

ArithmeticMedium

Question

The average weight of students in a class increases by 600 gm when some new students join the class. If the average weight of the new students is 3 kg more than the average weight of the original students, then the ratio of the number of original students to the number of new students is

Options

1 : 4

1 : 2

4 : 1

3 : 1

Solution

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,

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

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

$2.4m=0.6n$

$4m=n$

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

The answer is option C.