A shop had 630 story books. There were Malay, Chinese and English story books in the ratio of 3 : 6 : 5. When the shop assistant brought in another 369 new story books, the number of Malay story books was increased by 40% and the number of Chinese story books was increased by ¹₂.

1. What was the number of English story books that the shop assistant brought in?
2. What was the percentage increase in the number of English story books?

	Malay	Chinese	English	Total
Before	3 u	6 u	5 u	630
Change	+ 1.2 u	+ 3 u	+ ?	+ 369
After	4.2 u	9 u	9 u	999

Increase in the number of Malay story books
= 40% x 3 u
= ⁴⁰₁₀₀ x 3 u
= 1.2 u

Increase in the number of Chinese story books
= ¹₂ x 6 u
= 3 u

Total number of story books at first
= 3 u + 6 u + 5 u
= 14 u

14 u = 630

1 u = 630 ÷ 14 = 45

Increase in the number of Malay and Chinese story books
= 1.2 u + 3 u
= 4.2 u
= 4.2 x 45
= 189

Number of English story books brought in
= 369 - 189
= 180 

(b)
Number of English story books at first
= 5 u
= 5 x 45
= 225

Percentage increase in English story books
= ¹⁸⁰₂₂₅ x 100%
= 80%

Answer(s): (a) 180; (b) 80%