Question

If one orange cost Rs. 45, how many oranges can be bought for Rs. 72.

Answer 1

Hint: To solve this question, we will first of all calculate the number of oranges that can be bought in 1 Rupee. Then finally by using the unitary method, we will calculate the number of oranges that can be bought in Rs. 72.

Complete step by step answer:
Let us understand the concept first. The unitary method is a very useful method to find the value of n number of items if we have the value of a single item. So, suppose we have the value of 1 item, we can get the value of n items by multiplying the single value with n. And if we have the value of n items, then we can divide it by n to get the value of a single item.
Given that one orange cost Rs. 45. So, we will now calculate the number of oranges that can be bought in 1 Rupee. Using the unitary method, we have,
\[1\text{ orange}=Rs.45\]
\[\Rightarrow Rs.45=1\text{ orange}\]
\[\Rightarrow \operatorname{Re}.1=\dfrac{1}{45}\text{ oranges}\]
This is obtained by dividing by 45. Then in Rs. 72, we have a total of
\[\Rightarrow Rs.72=72\times \dfrac{1}{45}\text{oranges}\]
In Rs. 72, we have \[\dfrac{72}{45}\] oranges.
In Rs. 72, \[\dfrac{72}{45}=1.6\] oranges can be bought.

Note:
Another method to solve this question can be observing that as 1 orange is bought for Rs. 45 then 2 oranges can be bought for \[Rs.45\times 2=Rs.90.\] So, Rs. 90 will give us 2 oranges and we have Rs. 72 which means that as 72 < 90, clearly 2 oranges cannot be bought in Rs. 72. Hence, we will have more than 1 oranges in Rs. 72 but not 2 oranges in Rs. 72.