Question

My mother says, in her childhood petrol was $ {\text{Rs}}{\text{.1}} $ a litre. It is $ {\text{Rs}}{\text{.52}} $ per litre today. By what percentage has the price gone up?

Answer 1

Hint: This question can be solved by using the percentage calculation formula. In this question there are two different price rates of the petrol for two different time periods and we have to find how much the price of the petrol has increased between that time period in terms of percentage. In order to solve this question, we first find the increase in the price of the petrol in Rs. per litre then using the percentage increase formula we calculate the percentage increase in the price of the petrol.

Complete step-by-step answer:
Given:
The present price rate of the petrol $ = {\text{Rs}}{\text{.52 per litre}} $
The old price rate of the petrol $ = {\text{Rs}}{\text{.1 a litre}} $
So, the change or increase in the price of the petrol is the difference between the present price and the old price of the petrol.
Increase in the price $
 = 52 - 1\\
 = 51
 $
So, the increase in the price of the petrol is $ {\text{Rs}}{\text{.51 per litre}} $ between the old price and the present price.
And the percent increase in the price is calculated by the formula given below –
 $\Rightarrow \% {\text{increase = }}\dfrac{{{\text{increase in the price}}}}{{{\text{old price}}}} \times 100 $
Substituting the values of the increase in the price and the old price in the formula we get,
 $
\Rightarrow \% {\text{increase = }}\dfrac{{51}}{1} \times 100\\
 = 51 \times 100\\
 = 5100\%
 $
Therefore, the percentage increase in the price of the petrol is $ 5100\% $ .

Note: Make sure that the unit for the price rate for the petrol given in the question should be the same, if not then make them the same unit by using the required conversion formula. Then we can calculate the difference between two price rates and the percentage increase in the price rate of the petrol.