Question

If 18 dolls cost Rs.630. How many dolls can be bought for Rs.455?

Answer 1

Hint: In the above question we will use the concept of unitary method to find the number of dolls that can be bought for the given rupees. So, we will find the number of dolls that can be bought in Rs.1 and simplify it more to get the number of required dolls.

Complete step-by-step answer:
The unitary method is a technique that can be used to find the value of a quantity if we know that value of a unit quantity. So, for example if we have the cost of 5 ribbons as Rs. 10, then to find the cost of 10 ribbons, first we will find the cost of 1 unit, i.e 1 ribbon and then multiply with 10. So, the cost of 1 ribbon will be Rs. 10 divided by 5, i.e. Rs. 2. Then, the cost of 10 ribbons will be 2 times 10, i.e. Rs. 20. We can apply this method to solve this question.
We have been given that the cost of 18 dolls is Rs.630.

\[\Rightarrow \] Number of dolls in Rs.1 \[=\dfrac{18}{630}\]

Now, we have to find the number of dolls in Rs.455.

\[\Rightarrow \] Number of dolls in Rs.455 \[=\dfrac{18}{630}\times 450\]

On solving the above calculation, we get

Number of dolls in Rs.455 = 13.

Therefore, the number of dolls that can be bought Rs.455 is 13.


Note: Just be careful while doing calculation as there is a chance that you make a silly mistake and get the incorrect answer of the above question. Also, we can solve the above question by using direct proportion and we will get the same results. Also, remember the concept of unitary method as it will help you a lot in these types of questions.