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

1. Half of the rulers sold by Book Shop Y were orange rulers. How many orange 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 August, Book Shop Z sold 10 less yellow rulers than the number of yellow rulers sold in July. What was the percentage increase in the number of yellow rulers sold by Book Shop Z from July to August?

(a)
Number of blue rulers sold in Book Shop Y = 40
Number of yellow rulers sold in Book Shop Y = 60
Number of purple rulers sold in Book Shop Y = 80

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

Number of orange rulers sold in Book Shop Y
= 60 + 80 + 40
= 180

(b)
Number of blue rulers sold in Book Shop Y = 40 (Less) 
Number of blue rulers sold in Book Shop Z = 70

Number of yellow rulers sold in Book Shop Y = 60 (More)
Number of yellow rulers sold in Book Shop Z = 50

Number of purple rulers sold in Book Shop Y = 80 (Equal)
Number of purple rulers sold in Book Shop Z = 80

Number of orange rulers sold in Book Shop Y = 180 (More) 
Number of orange rulers sold in Book Shop Z = 60 

Colour(s) of rulers that Book Shop Y sold less than Book Shop Z = Blue (B)

(c)
Percentage decrease in the number of yellow rulers sold by Book Shop Z from July to August
= ¹⁰₅₀ x 100%
= ¹₅ x 100%
= 20%

Answer(s): (a) 180; (b) B; (c) 20%