Question

Out of 100 students in a school, 42 take English, 35 take Chinese and 30 take French. 20 take none of the subjects, 9 take French and English, 10 take French and Chinese, 11 take English and Chinese. Find the number of students who take 3 subjects?​

Answer 1

1 student

Explanation:

From the Vann diagram attached below,

Let x represent the number of students who took 3 subjects.

Therefore,

100 = (42-9-11-x)+11+x+9+10+(35-10-11-x)+(30-9-10-x)+20

100 = 22-x+11+x+9+10+14-x+11-x+20

100 = 97-2x

2x = 100-97

2x = 3

x = 3/2.

x = 1.5

x = 1 student