Question

If a car covers $ 82.5 $ km in $ 5.5 $ litres of petrol, how much distance will it cover in $ 13.2 $ litres of petrol?
(A) $ 120 $
(B) $ 198 $
(C) $ 200 $
(D) $ 150 $

Answer 1

Hint: Use unitary method, first try to find out the distance covered by car in $ 1 $ litre of petrol, later on multiply the result with 13.2 to get the required result. In essence, this method is used to find the value of a unit from the value of a multiple, and hence the value of a multiple

Complete step-by-step answer:
The unitary method is a technique for solving a problem by first finding the value of a single unit, and then finding the necessary value by multiplying the single unit value. In essence, this method is used to find the value of a unit from the value of a multiple, and hence the value of a multiple.
We have been given that a car travels 82.5 km in 5.5 litres of petrol, i.e
In $ 5.5\, $ litres of petrol, distance covered by car $ = 82.5\,km $
Lets calculate the distance travelled by car for unit liters consumption ,that is for 1 litre
 $ \Rightarrow $ In $ 1 $ litre of petrol, distance covered by car $ = \dfrac{{82.5}}{{5.5}} = \dfrac{{825}}{{55}} = \dfrac{{75}}{5} = 15 $
Now let's multiply the obtained value with 13.5 to get the required answer,
 $ \Rightarrow $ distance covered by car in $ 13.2 $ litre of petrol $ = 15 \times 13.2 $ $ = 198.0\,\,km $
So, the correct answer is “198 km.

Note: you can also use direct proportion method
 $ \dfrac{{82.5}}{{5.5}} = \dfrac{x}{{13.2}} $
 $ \Rightarrow 5.5x = 82.5 \times 13.2 $
 $ \Rightarrow x = \dfrac{{82.5 \times 13.2}}{{5.5}} = \,198\;km. $