PSLE
School camp skirts were available in 4 colours: red, green, black and brown. At the camp, each pupils chose one skirt. The pie chart represents the pupils' choice of skirt colours. 30 pupils chose brown skirts. The pupils' choice of skirt colours is also represented by the bar graph. The bar that shows the number of pupils who chose red skirts has not been drawn. How many pupils chose red skirts?

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

From the bar graph,
Number of pupils who chose black = Number of pupils who chose green = 50 

¹₄ of the pie chart = 50
⁴₄ of the pie chart = 4 x 50 = 200

Total number of pupils = 200

Number of pupils who chose red skirts
= 200 - 50 - 50 - 30
= 70

Answer(s): 70