PSLE
Book Shops X and Y sell staplers of four colours. The bar graphs show the number of staplers sold by each shop in September. The bar for the number orange staplers sold by Book Shop X has not been drawn.

1. Half of the staplers sold by Book Shop X were orange staplers. How many orange staplers did Book Shop X sell?
2. Which colour(s) of staplers did Book Shop X sell less than Book Shop Y? Give your answer(s) in letter(s) in alphabetical order. (Eg Blue, Red = B, R)
3. In October, Book Shop Y sold 15 less purple staplers than the number of purple staplers sold in September. What was the percentage increase in the number of purple staplers sold by Book Shop Y from September to October?

(a)
Number of yellow staplers sold in Book Shop X = 15
Number of purple staplers sold in Book Shop X = 50
Number of pink staplers sold in Book Shop X = 20

Since orange staplers sold in Book Shop X is half of the staplers sold by Book Shop X, the total of purple staplers, pink staplers and yellow staplers is equal to orange staplers.

Number of orange staplers sold in Book Shop X
= 50 + 20 + 15
= 85

(b)
Number of yellow staplers sold in Book Shop X = 15 (Less) 
Number of yellow staplers sold in Book Shop Y = 50

Number of purple staplers sold in Book Shop X = 50 (More)
Number of purple staplers sold in Book Shop Y = 20

Number of pink staplers sold in Book Shop X = 20 (Equal)
Number of pink staplers sold in Book Shop Y = 20

Number of orange staplers sold in Book Shop X = 85 (More) 
Number of orange staplers sold in Book Shop Y = 45 

Colour(s) of staplers that Book Shop X sold less than Book Shop Y = Yellow (Y)

(c)
Percentage decrease in the number of purple staplers sold by Book Shop Y from September to October
= ¹⁵₂₀ x 100%
= ³₄ x 100%
= 75%

Answer(s): (a) 85; (b) Y; (c) 75%