subhajeet wrote:

At Daifu university, 40% of all students are members of both a chess club and a swim team. If 20% of members of the swim team are not members of the chess club, what percentage of all Daifu students are members of the swim team?

20%

30%

40%

50%

60%

I have solved the question differently. Can anybody please correct me as where did I go wrong.

From the attached figure we get B = 40% and C = 20%

so the number of students who are member of swim team is 40%+40% = 80%

The red part is not correct.

Assume there are total of 100 students. 40 students are members of both clubs (B in your diagram). We are told that: "20% of members

of the swim team are not members of the chess club", thus if S is a # of members of swim team then S/5 is the segment you denoted as C.

40+S/5=S --> S=50.

Answer: D.

Or another way: since "20% of members

of the swim team are not members of the chess club" then the rest 80% of members

of the swim team ARE members of the chess club, so members of both clubs: 0.8*S=40 --> S=50.

Answer: D.

Hope it's clear.

Bunnel: Thanks for the explanation. Here it is mentioned as 40% of the students are members of both clubs so it means 0.4S. so do we here take it as 40 students???

I am not able to understand why are u taking here the base as 40 students and not 40% of students.