SSC CHSL 2021 PYQ — Question 76

The correct answer is Option 2 i.e. 16$\frac{1}{2}$%.
Let the consumption of petrol by the consumer be 1 litre and the price is 100 rupees per litre.
So, the expenditure is 100 rupees.
When increased by 20%, the price per litre becomes 120 rupees.
Let the new amount of petrol be x litres.
Now, 1 litre costs 120 rupees.
So, x liters cost 120x
 .
But the expenditure remains constant.
So, we get,
120x = 100 ⇒ x = 100/120

⇒x = 0.83
So, the new amount is 0.83(1/3)litres.

The amount decreased is 1 − 0.83(1/3) = 0.16(2/3) litres.

So, the decreased percentage is {0.16(2/3)} /1 × 100 = 16$\frac{1}{2}$%.

Therefore, from equation 1.1, we get the correct option to the given question is 16$\frac{1}{2}$%.

Hence, the correct answer is 16$\frac{1}{2}$%.