PSLE
Stationery Shops M and N sell notebooks of four colours. The bar graphs show the number of notebooks sold by each shop in July. The bar for the number blue notebooks sold by Stationery Shop M has not been drawn.

1. Half of the notebooks sold by Stationery Shop M were blue notebooks. How many blue notebooks did Stationery Shop M sell?
2. Which colour(s) of notebooks did Stationery Shop M sell less than Stationery Shop N? Give your answer(s) in letter(s) in alphabetical order. (Eg Blue, Red = B, R)
3. In August, Stationery Shop N sold 10 more green notebooks than the number of green notebooks sold in July. What was the percentage increase in the number of green notebooks sold by Stationery Shop N from July to August?

(a)
Number of green notebooks sold in Stationery Shop M = 250
Number of purple notebooks sold in Stationery Shop M = 250
Number of yellow notebooks sold in Stationery Shop M = 100

Since blue notebooks sold in Stationery Shop M is half of the notebooks sold by Stationery Shop M, the total of green notebooks, purple notebooks and yellow notebooks is equal to blue notebooks.

Number of blue notebooks sold in Stationery Shop M
= 250 + 250 + 100
= 600

(b)
Number of green notebooks sold in Stationery Shop M = 250 (More)
Number of green notebooks sold in Stationery Shop N = 50

Number of purple notebooks sold in Stationery Shop M = 250 (Equal)
Number of purple notebooks sold in Stationery Shop N = 250

Number of yellow notebooks sold in Stationery Shop M = 100 (Less) 
Number of yellow notebooks sold in Stationery Shop N = 250

Number of blue notebooks sold in Stationery Shop M = 600 (More) 
Number of blue notebooks sold in Stationery Shop N = 125 

Colour(s) of notebooks that Stationery Shop M sold less than Stationery Shop N = Yellow (Y)

(c)
Percentage increase in the number of green notebooks sold by Stationery Shop N from July to August
= ¹⁰₅₀ x 100%
= ¹₅ x 100%
= 20%

Answer(s): (a) 600; (b) Y; (c) 20%