A book store had 520 story books. There were Chinese, English and Malay story books in the ratio of 1 : 8 : 4. When the book store assistant brought in another 224 new story books, the number of Chinese story books was increased by 60% and the number of English story books was increased by ¹₂.

1. What was the number of Malay story books that the book store assistant brought in?
2. What was the percentage increase in the number of Malay story books?

	Chinese	English	Malay	Total
Before	1 u	8 u	4 u	520
Change	+ 0.6 u	+ 4 u	+ ?	+ 224
After	1.6 u	12 u	5 u	744

Increase in the number of Chinese story books
= 60% x 1 u
= ⁶⁰₁₀₀ x 1 u
= 0.6 u

Increase in the number of English story books
= ¹₂ x 8 u
= 4 u

Total number of story books at first
= 1 u + 8 u + 4 u
= 13 u

13 u = 520

1 u = 520 ÷ 13 = 40

Increase in the number of Chinese and English story books
= 0.6 u + 4 u
= 4.6 u
= 4.6 x 40
= 184

Number of Malay story books brought in
= 224 - 184
= 40 

(b)
Number of Malay story books at first
= 4 u
= 4 x 40
= 160

Percentage increase in Malay story books
= ⁴⁰₁₆₀ x 100%
= 25%

Answer(s): (a) 40; (b) 25%