Question

The cost of 1 litre of milk is Rs \[20\dfrac{2}{5}\]. Find the cost of 5 litres of milk.

Answer 1

Hint: Cost of one litre of milk is given in the question. Objective is to find the cost of 5 litre of milk. For this, we’ll simply multiply the cost of one litre of milk with 5 to get the desired cost of 5 litres of milk.

Complete step-by-step answer:
Now, will first simplify given fraction in question i.e. \[20\dfrac{2}{5}\]
So, \[20\dfrac{2}{5}\]= \[20+\dfrac{2}{5}\]
= \[\dfrac{102}{5}\]
Now, we have, \[20\dfrac{2}{5}\]= \[\dfrac{102}{5}\]
According to question, the cost of 1 litre of milk is Rs \[20\dfrac{2}{5}\]
Hence, the cost of 1 litre of milk is Rs \[\dfrac{102}{5}\]
Therefore, the cost of 5 litre of milk is equal to 5 times the cost of 1 litre of milk.
So, cost of 5 litre of milk is Rs \[\left( 5\times \dfrac{102}{5} \right)\]
\[=\left( \dfrac{510}{5} \right)\]
\[=102\]

So, the cost of 5 litres of milk is Rs 102.

Note: Sometimes, in question, it is asked to find the cost of 1 litre of milk if the cost of 12 litres of milk is given. For this type of question, we need to divide the total cost of 12 litres of milk by 12 in order to get the cost of 1 litre of milk. Don't confuse this type of question with the above question in which we need to find the cost of 5 litres milk. We can check if the cost of 5 litres of milk is correct or not. For this divide the cost of 5 litres of milk by 5. If we get the answer as 1 litre of milk. Then, the found cost of 5 litres of milk is correct otherwise there is definitely a mistake in solving the question.