PSLE
Stores X and Y sell post-it-pads of four colours. The bar graphs show the number of post-it-pads sold by each shop in April. The bar for the number purple post-it-pads sold by Store X has not been drawn.

1. Half of the post-it-pads sold by Store X were purple post-it-pads. How many purple post-it-pads did Store X sell?
2. Which colour(s) of post-it-pads did Store X sell less than Store Y? Give your answer(s) in letter(s) in alphabetical order. (Eg Blue, Red = B, R)
3. In May, Store Y sold 15 less green post-it-pads than the number of green post-it-pads sold in April. What was the percentage increase in the number of green post-it-pads sold by Store Y from April to May?

(a)
Number of yellow post-it-pads sold in Store X = 25
Number of green post-it-pads sold in Store X = 225
Number of pink post-it-pads sold in Store X = 200

Since purple post-it-pads sold in Store X is half of the post-it-pads sold by Store X, the total of green post-it-pads, pink post-it-pads and yellow post-it-pads is equal to purple post-it-pads.

Number of purple post-it-pads sold in Store X
= 225 + 200 + 25
= 450

(b)
Number of yellow post-it-pads sold in Store X = 25 (Less) 
Number of yellow post-it-pads sold in Store Y = 175

Number of green post-it-pads sold in Store X = 225 (More)
Number of green post-it-pads sold in Store Y = 125

Number of pink post-it-pads sold in Store X = 200 (Equal)
Number of pink post-it-pads sold in Store Y = 200

Number of purple post-it-pads sold in Store X = 450 (More) 
Number of purple post-it-pads sold in Store Y = 250 

Colour(s) of post-it-pads that Store X sold less than Store Y = Yellow (Y)

(c)
Percentage decrease in the number of green post-it-pads sold by Store Y from April to May
= ¹⁵₁₂₅ x 100%
= ³₂₅ x 100%
= 12%

Answer(s): (a) 450; (b) Y; (c) 12%