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

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

From the bar graph,
Number of participants who chose black = Number of participants who chose white = 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 grey vests
= 180 - 45 - 45 - 39
= 51

Answer(s): 51