PSLE
Stationery Kiosks Y and Z sell staplers of four colours. The bar graphs show the number of staplers sold by each shop in November. The bar for the number blue staplers sold by Stationery Kiosk Y has not been drawn.

1. Half of the staplers sold by Stationery Kiosk Y were blue staplers. How many blue staplers did Stationery Kiosk Y sell?
2. Which colour(s) of staplers did Stationery Kiosk Y sell less than Stationery Kiosk Z? Give your answer(s) in letter(s) in alphabetical order. (Eg Blue, Red = B, R)
3. In December, Stationery Kiosk Z sold 10 less pink staplers than the number of pink staplers sold in November. What was the percentage increase in the number of pink staplers sold by Stationery Kiosk Z from November to December?

(a)
Number of yellow staplers sold in Stationery Kiosk Y = 80
Number of pink staplers sold in Stationery Kiosk Y = 120
Number of purple staplers sold in Stationery Kiosk Y = 100

Since blue staplers sold in Stationery Kiosk Y is half of the staplers sold by Stationery Kiosk Y, the total of pink staplers, purple staplers and yellow staplers is equal to blue staplers.

Number of blue staplers sold in Stationery Kiosk Y
= 120 + 100 + 80
= 300

(b)
Number of yellow staplers sold in Stationery Kiosk Y = 80 (Less) 
Number of yellow staplers sold in Stationery Kiosk Z = 120

Number of pink staplers sold in Stationery Kiosk Y = 120 (More)
Number of pink staplers sold in Stationery Kiosk Z = 100

Number of purple staplers sold in Stationery Kiosk Y = 100 (Equal)
Number of purple staplers sold in Stationery Kiosk Z = 100

Number of blue staplers sold in Stationery Kiosk Y = 300 (More) 
Number of blue staplers sold in Stationery Kiosk Z = 80 

Colour(s) of staplers that Stationery Kiosk Y sold less than Stationery Kiosk Z = Yellow (Y)

(c)
Percentage decrease in the number of pink staplers sold by Stationery Kiosk Z from November to December
= ¹⁰₁₀₀ x 100%
= ¹₁₀ x 100%
= 10%

Answer(s): (a) 300; (b) Y; (c) 10%