Question

A motor car consumes one liter petrol when it covers a distance of 9 km and the cost on account of petrol for a journey of 360km by that car is Rs. 102.40. What will be the cost on account of petrol for covering a distance of 600km. by a car which requires one liter petrol to cover a distance of 7.5km?

Answer 1

Hint: The given question gives a detail description of motor car running at some rate for per kilometer of journey and we need to find the price for the asked journey for certain kilometers and at a fixed fuel rate price, here we have to get the unit kilo meter price and then solve for the given kilometers.

Complete step by step solution:
The given question describes the average consumption of fuel for a car and the total cost for the journey, and we are asked to find the cost for the other car whose average fuel consumption is given and the cost for the fuel used have to be obtained from the previous car, on solving we get:
 \[
   \Rightarrow \text{average rate for first car} = \dfrac{{360km}}{{9km}} = 40 \text{ liter for the complete journey} \\
   \Rightarrow \text{cost taken for the whole journey} = Rs.102.40 \\
   \Rightarrow \text{cost for 1liter} = \dfrac{{102.40}}{{40}} = Rs.2.56\,per\,litre \\
 \]
Using the cost for 1litre from first car we can use this value for calculation for the whole journey for the second car, on solving we get:
 \[
   \Rightarrow \text{average rate for second car} = \dfrac{{360km}}{{7.5km}} = 48\text{liter for complete journey} \\
   \Rightarrow \text{cost taken for the whole journey} = 48 \times 2.56Rs = 122.88Rs \\
 \]
Hence the cost of journey from the second car is Rs.122.88.
So, the correct answer is “ Rs.122.88.”.

Note: The given question needs to be solved by converting the cost per liter for fuel from the first car and then to apply it for the second car, this kind of question in which relations have to be established are to be solved like this only.