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

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

(a)
Number of pink rulers sold in Book Shop Y = 50
Number of green rulers sold in Book Shop Y = 80
Number of purple rulers sold in Book Shop Y = 100

Since blue rulers sold in Book Shop Y is half of the rulers sold by Book Shop Y, the total of green rulers, purple rulers and pink rulers is equal to blue rulers.

Number of blue rulers sold in Book Shop Y
= 80 + 100 + 50
= 230

(b)
Number of pink rulers sold in Book Shop Y = 50 (Less) 
Number of pink rulers sold in Book Shop Z = 60

Number of green rulers sold in Book Shop Y = 80 (More)
Number of green rulers sold in Book Shop Z = 50

Number of purple rulers sold in Book Shop Y = 100 (Equal)
Number of purple rulers sold in Book Shop Z = 100

Number of blue rulers sold in Book Shop Y = 230 (More) 
Number of blue rulers sold in Book Shop Z = 30 

Colour(s) of rulers that Book Shop Y sold less than Book Shop Z = Pink (P)

(c)
Percentage decrease in the number of green rulers sold by Book Shop Z from September to October
= ¹⁵₅₀ x 100%
= ³₁₀ x 100%
= 30%

Answer(s): (a) 230; (b) P; (c) 30%