PSLE
School camp windbreakers were available in 4 colours: red, grey, green and black. At the camp, each participants chose one windbreaker. The pie chart represents the participants' choice of windbreaker colours. 39 participants chose black windbreakers. The participants' choice of windbreaker colours is also represented by the bar graph. The bar that shows the number of participants who chose red windbreakers has not been drawn. How many participants chose red windbreakers?

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

From the bar graph,
Number of participants who chose green = Number of participants who chose grey = 54 

¹₄ of the pie chart = 54
⁴₄ of the pie chart = 4 x 54 = 216

Total number of participants = 216

Number of participants who chose red windbreakers
= 216 - 54 - 54 - 39
= 69

Answer(s): 69