Question

A car covers a distance of 14.75 km in one liter of petrol. How much distance will it cover in 15.5 liters of petrol (in km)?

Answer 1

Hint: For the solution of this question, we shall use the unitary method. In the unitary method, first we calculate the value of a single unit, and then multiply it with the required value. So, in this question, we have already been given that in 1 liter petrol, the car runs for 14.75 km, so, to find the distance that the car can cover in 15.5 liters of petrol, we shall multiply 14.75 by 15.5 to calculate the distance.

Complete step by step answer:
So, to get started with the solution, let us first learn about the unitary method.
Let us take an example as below.
A shopkeeper sells 5 pencils for Rs. 15. What will be the cost of 50 such pencils?
Let us try to solve this question now.
Cost of 5 pencils = Rs. 15
Cost of 1 pencil = \[Rs.\ \ \left( \dfrac{15}{5} \right)\] = Rs. 3
Cost of 50 pencils = \[Rs.\ \ \left( 50\ \ \times \ \ 3 \right)\] = Rs. 150
So, that shopkeeper will sell 50 such pencils for Rs. 150. In other words, the cost of 50 pencils is Rs. 150.
Focusing on the question,
Distance covered by the car in 1 liter of petrol = 14.75 km
Distance covered by the car in 15.5 liter of petrol = \[14.75\ \ \times \,\,15.5\] = 228.625 km

So, the distance the car can cover with 15.5 liters of petrol is 228.625 km. In other words, for covering a distance of 228.625 km, the car needs 15.5 liters of petrol.

Note: This is a simple question which requires basic calculations. The students must know when to multiply and when to divide in such a question. Here, we have to directly multiply as the unit quantity was known. But, by mistake, if we divide the two numbers, the answer can come out to be wrong. Students must read the question carefully and understand that it requires the concept of unitary method to be applied and not speed-distance-time concept.