PSLE
The pie charts show the number of each type of stationery in 2 stationery boxes, B and C. The total number of stationery in Box B is thrice the total number of stationery in Box C.

1. Find the percentage of pens in Box B.
2. What fraction of stationery in Box C is pens?
3. The number of pens in Box B is 105. Find the number of pens in Box C.

(a)
^90°_360° = 25% of stationery in Box B

Percentage of notebooks in Box B = 25%

Percentage of pens in Box B
= 100% - 40% - 25%
= 35%

(b)
Percentage of pens in Box C
= 100% - 75% - 15%
= 10%

Fraction of stationery in Box C that is pens
= ¹₁₀

(c)
35% of stationery in Box B = 105
1% of stationery in Box B = 105 ÷ 35 = 3 
100% of the stationery in Box B = 100 x 3 = 300

Number of stationery in Box C
= 300 ÷ 3
= 100

100% of stationery in Box C = 100
1% of stationery in Box B = 100 ÷ 100 = 1
10% of stationery in Box B = 10 x 1 = 10  

Number of pens in Box C = 10

Answer(s): (a) 35%; (b) ¹₁₀; (c) 10