PSLE
School camp sweaters were available in 4 colours: red, black, blue and pink. At the camp, each participants chose one sweater. The pie chart represents the participants' choice of sweater colours. 38 participants chose red sweaters. The participants' choice of sweater colours is also represented by the bar graph. The bar that shows the number of participants who chose black sweaters has not been drawn. How many participants chose black sweaters?

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

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

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

Total number of participants = 180

Number of participants who chose black sweaters
= 180 - 45 - 45 - 38
= 52

Answer(s): 52