Question

In a school library the ratio of science books to that of math books is 4:5 If there are 384 science books find the number of math books in the library

Answer 1

Science: Math= 4:5
384:x= 4:5
PRODUCT OF EXTREMES = PRODUCT OF MEANS
384*5= x* 4
1920= x* 4
x= 1920/4
x= 480

Answer 2

The number of maths books in the library is 480.

Given, the ratio of science books to maths books is 4:5.

Let us consider the common multiple to be 'x'.

So, Science books are = 4x

Similarly, Maths books are = 5x

In the question, it is mentioned that Science books are 384 in number .

So, we can write it as:

4x = 384

Or, x = 384/4 = 96

Thus no. of maths books = 5x = 5(96) = 480

There are 480 maths books.