PSLE
School camp vests were available in 4 colours: blue, yellow, white and pink. At the camp, each pupils chose one vest. The pie chart represents the pupils' choice of vest colours. 40 pupils chose yellow vests. The pupils' choice of vest colours is also represented by the bar graph. The bar that shows the number of pupils who chose white vests has not been drawn. How many pupils chose white vests?

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

From the bar graph,
Number of pupils who chose blue = Number of pupils who chose pink = 45 

¹₄ of the pie chart = 45
⁴₄ of the pie chart = 4 x 45 = 180

Total number of pupils = 180

Number of pupils who chose white vests
= 180 - 45 - 45 - 40
= 50

Answer(s): 50