PSLE
School camp sweaters were available in 4 colours: black, yellow, blue and pink. At the camp, each pupils chose one sweater. The pie chart represents the pupils' choice of sweater colours. 35 pupils chose pink sweaters. The pupils' choice of sweater colours is also represented by the bar graph. The bar that shows the number of pupils who chose black sweaters has not been drawn. How many pupils chose black sweaters?

    
From the pie graph,
fraction of pupils who chose blue or yellow
= ^90°_360°
= ¹₄

From the bar graph,
Number of pupils who chose blue = Number of pupils who chose yellow = 42 

¹₄ of the pie chart = 42
⁴₄ of the pie chart = 4 x 42 = 168

Total number of pupils = 168

Number of pupils who chose black sweaters
= 168 - 42 - 42 - 35
= 49

Answer(s): 49