Question

Rita had enough money to buy 15 books for RS 30 each. If the price of each book increases resulting in the total cost increase of rupees 45, how many books can she buy now? How much money will be left with her?

Answer 1

Hint: First find the total money Rita has. Now, find the total cost of the book after increment. After that find the increased cost per book. Then, divide the total amount by the new price of the book and take the whole number, which will be the total number of the books. Now, multiply the number of the books by the new price of the book. After that, subtract it from the money Rita has. The money will be left with her.

Complete step by step answer:
Given, Rita had enough money to buy 15 books for RS 30 each if the price of each book increased resulting in the total cost increase of rupees 45.
The total money Rita have,
$\Rightarrow 30 \times 15 = {\text{Rs}}{\text{. 450}}$
Now, total price of the book after increment of Rs. 45,
$\Rightarrow 450 + 45 = {\text{Rs}}{\text{. 495}}$
Find the new price of per book,
$\Rightarrow \dfrac{{495}}{{15}} = 33$
So, the new price of one book is Rs. 33.
Now, find the number of books bought at new price,
$\Rightarrow \dfrac{{450}}{{33}} = 13.\overline {63} $
So, the number of books bought is 13.
Total money spent on the books is,
$\Rightarrow 13 \times 33 = 429$
The money left with Rita is,
$\Rightarrow 450 - 429 = 21$

Hence, the number of books she can buy is 13 and the money left with her is Rs. 21.

Note:
The students might make mistakes in the increase of the price of books by increasing the money Rita has.
Students are likely to make mistakes in questions which have units in different forms. Students
are advised to use common conversions first to convert all the values in same unit and then do
calculations. Some conversions are:
$1Kg = 1000grams$
$1dozen = 12units$
$Rs.1 = 100paisa$