PSLE
Shops Q and R sell post-it-pads of four colours. The bar graphs show the number of post-it-pads sold by each shop in October. The bar for the number blue post-it-pads sold by Shop Q has not been drawn.

1. Half of the post-it-pads sold by Shop Q were blue post-it-pads. How many blue post-it-pads did Shop Q sell?
2. Which colour(s) of post-it-pads did Shop Q sell less than Shop R? Give your answer(s) in letter(s) in alphabetical order. (Eg Blue, Red = B, R)
3. In November, Shop R sold 10 more green post-it-pads than the number of green post-it-pads sold in October. What was the percentage increase in the number of green post-it-pads sold by Shop R from October to November?

(a)
Number of green post-it-pads sold in Shop Q = 90
Number of yellow post-it-pads sold in Shop Q = 100
Number of orange post-it-pads sold in Shop Q = 20

Since blue post-it-pads sold in Shop Q is half of the post-it-pads sold by Shop Q, the total of green post-it-pads, yellow post-it-pads and orange post-it-pads is equal to blue post-it-pads.

Number of blue post-it-pads sold in Shop Q
= 90 + 100 + 20
= 210

(b)
Number of green post-it-pads sold in Shop Q = 90 (More)
Number of green post-it-pads sold in Shop R = 50

Number of yellow post-it-pads sold in Shop Q = 100 (Equal)
Number of yellow post-it-pads sold in Shop R = 100

Number of orange post-it-pads sold in Shop Q = 20 (Less) 
Number of orange post-it-pads sold in Shop R = 70

Number of blue post-it-pads sold in Shop Q = 210 (More) 
Number of blue post-it-pads sold in Shop R = 50 

Colour(s) of post-it-pads that Shop Q sold less than Shop R = Orange (O)

(c)
Percentage increase in the number of green post-it-pads sold by Shop R from October to November
= ¹⁰₅₀ x 100%
= ¹₅ x 100%
= 20%

Answer(s): (a) 210; (b) O; (c) 20%