PSLE
School camp shirts were available in 4 colours: purple, red, black and grey. At the camp, each participants chose one shirt. The pie chart represents the participants' choice of shirt colours. 37 participants chose red shirts. The participants' choice of shirt colours is also represented by the bar graph. The bar that shows the number of participants who chose black shirts has not been drawn. How many participants chose black shirts?

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

From the bar graph,
Number of participants who chose purple = Number of participants who chose grey = 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 shirts
= 180 - 45 - 45 - 37
= 53

Answer(s): 53