If the price of petrol is increased by 20%, by what percentage the consumption should be decreased by the consumer, if the expenditure on petrol remains unchanged?

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Detailed Solution

Concept- In this case, we can assume that the consumer initially used 1 liter of gasoline at a cost of 100 rupees. The price of 1 liter of gasoline after a 20% rise can then be determined. With the help of this, we can determine the lowered amount of gasoline for the same price and the percentage decrease, which will be the response we need.
In this question, we are required to determine the percentage of gasoline usage that the user should reduce in order to maintain a 20% price increase while maintaining a constant expenditure.
Assume that each liter of gasoline consumed by the user costs 100 rupees.
Therefore, the cost is 100 rupees.
The cost per liter rises to 120 rupees when increased by 20%.
Let's say that the new gasoline volume is x liters.
A liter now costs 120 rupees.
So, x liters cost 120x
But the expenditure remains constant.
So, we get,
120x = 100
x =