Question

In a library, the ratio of maths books to science books is 3 : 2 and the ratio of science books to history books is 1 : 3. If the total number of books is 220, how many maths books are there?

Answer 1

60 maths books

Explanation:

Let the following be:

• Maths books = m
• Science books = s
• History books = h

And we have ratios and sum:

• m/s = 3/2
• s/h = 1/3
• m+s+h = 220

From the ratios we get:

• m = 3s/2
• h= 3s

Considering the above in the sum of books:

• m+s+h = 220
• 3s/2 + s + 3s = 220
• 3s + 2s + 6s = 2*220
• 11s = 440
• s = 440/11
• s = 40

Number of maths books:

• m = 3s/2 = 3*40/2 = 60