PSLE
Stationery Shops Y and Z sell post-it-pads of four colours. The bar graphs show the number of post-it-pads sold by each shop in November. The bar for the number pink post-it-pads sold by Stationery Shop Y has not been drawn.

1. Half of the post-it-pads sold by Stationery Shop Y were pink post-it-pads. How many pink post-it-pads did Stationery Shop Y sell?
2. Which colour(s) of post-it-pads did Stationery Shop Y sell less than Stationery Shop Z? Give your answer(s) in letter(s) in alphabetical order. (Eg Blue, Red = B, R)
3. In December, Stationery Shop Z sold 15 more yellow post-it-pads than the number of yellow post-it-pads sold in November. What was the percentage increase in the number of yellow post-it-pads sold by Stationery Shop Z from November to December?

(a)
Number of yellow post-it-pads sold in Stationery Shop Y = 250
Number of orange post-it-pads sold in Stationery Shop Y = 225
Number of blue post-it-pads sold in Stationery Shop Y = 50

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

Number of pink post-it-pads sold in Stationery Shop Y
= 250 + 225 + 50
= 525

(b)
Number of yellow post-it-pads sold in Stationery Shop Y = 250 (More)
Number of yellow post-it-pads sold in Stationery Shop Z = 75

Number of orange post-it-pads sold in Stationery Shop Y = 225 (Equal)
Number of orange post-it-pads sold in Stationery Shop Z = 225

Number of blue post-it-pads sold in Stationery Shop Y = 50 (Less) 
Number of blue post-it-pads sold in Stationery Shop Z = 250

Number of pink post-it-pads sold in Stationery Shop Y = 525 (More) 
Number of pink post-it-pads sold in Stationery Shop Z = 250 

Colour(s) of post-it-pads that Stationery Shop Y sold less than Stationery Shop Z = Blue (B)

(c)
Percentage increase in the number of yellow post-it-pads sold by Stationery Shop Z from November to December
= ¹⁵₇₅ x 100%
= ¹₅ x 100%
= 20%

Answer(s): (a) 525; (b) B; (c) 20%