Question

A survey carried out on 40 students about when they did their homework over the weekend
F=(homework done on friday)
S=(homework done on saturday/Sunday )
n(f)=20,n(s)=29
How many did both days ?

Answer 1

b did both
draw Venn diagram

fri---both- weekend

|20-b | b |29-b|

20-b + b + 29-b = 40

49 - b = 40

b = 9

11 fri , 9 both , 20 weekend