PSLE
School camp blazers were available in 4 colours: grey, pink, black and gold. At the camp, each contestants chose one blazer. The pie chart represents the contestants' choice of blazer colours. 30 contestants chose gold blazers. The contestants' choice of blazer colours is also represented by the bar graph. The bar that shows the number of contestants who chose grey blazers has not been drawn. How many contestants chose grey blazers?

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

From the bar graph,
Number of contestants who chose black = Number of contestants who chose pink = 60 

¹₄ of the pie chart = 60
⁴₄ of the pie chart = 4 x 60 = 240

Total number of contestants = 240

Number of contestants who chose grey blazers
= 240 - 60 - 60 - 30
= 90

Answer(s): 90