# GMAT Question of the Day: Probability

At a certain business school, 400 students are members of the sailing club, the wine club, or both. If 200 students are members of the wine club and 50 students are members of both clubs, what is the probability that a student chosen at random is a member of the sailing club?

A. 1/2
B. 5/8
C. 1/4
D. 3/8
E. 3/5

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1. Krishna Mohan says:

B. 250/400 = 5/8

2. Yeganeh says:

Sorry, but it seems that the answer is A because, 200 students are members of the wine club and other remaining students are members of the sailing club or both. So the probability will be:
200/400 = 1/2

3. Milind says:

It should be B.

There are 200 members of wine club, x of sailing club and 50 common. That means that sailing club will have 200+x-50=400
=> x=250 members [ n(A) + n(B) – n(A intersection B) = n(AUB)

The probability should be 250/400 = 5/8

4. aJ says:

a

5. vishal says:

b

B

7. gmat_guy says:

A.

“If 200 students are members of the wine club and 50 students are members of both clubs…”. I assume this to mean that there are 200 students of the wine club; of that 200, 50 are also in the sailing club. This means that there are 150 students in the wine club only; 50 students in both; and 200 students in the sailing club only.

I think others are reading this and thinking it means there are 200 students in the wine club only; however, it does not state that.

B

10. shyam says:

take GMAT team..Is the question ambiguous??i think answer is A

11. chinnu says:

i think the answer is 200/400=1/2 as it is not given that 200 members are the members of wine club only

12. bluebells says:

B.

Well, the question asks what is the probability that the member chosen is from sailing club. It does not mention “what is the probability that the member chosen is from sailing club ONLY”. So as per the question, the member should be in the sailing club…does not matter if he also belongs to wine club.

hence … 250/400 = 5/8.

13. daveparthiv says:

It has to 5/8.

Sailing Club: 200 + 50 (both) out of 400

Probability = 250/400 = 5/8

14. jaspreet says:

sailing club= total- win club + both= 250. probability 250/400 B is ans.

15. sumanth toom says:

In continuation of the explanation given by ‘gmat_guy.
“â€œIf 200 students are members of the wine club and 50 students are members of both clubsâ€¦â€. I assume this to mean that there are 200 students of the wine club; of that 200, 50 are also in the sailing club. This means that there are 150 students in the wine club only; 50 students in both; and 200 students in the sailing club only.”

==>Only wine club students = 150, Total students = 400. So probability of finding only wine club student = P(w) = 150/400= 3/8.
So P’(W) is probability of finding a non-only-wine (which is a wine & sail or a sail student) = 1 – 3/8 = 5/8. the correct answer..

A better way of solving is to directly find out P(S) = 250/400 = 5/8.

16. Deeks says:

B

18. Rahul says:

A

19. doppelganger says:

A

20. Rajib Banerjee says:

B 5/8.

n(S Union W) = n(S) + n(W) – n(S Intersection W)
400 = n(S) + 200 – 50
=> n(S) = 250
Therefore, Reqd Probability = 250/400 = 5/8

21. AT says:

It’s A.

Total: 400

Wine Only: 200
Wine and Sailing: 50
Sailing Only: 150

There are 200 members of the Sailing Club of whom some are also members of the Wine Club. 200/400 = 1/2 = Answer A.

22. kingfisher says:

B

23. Keerthi says:

250/400 = 5/8 B is the answer

24. Aliva says:

oh God thnx….I got it right.
A
Thanks to Gmat Team for the OA

If you observe you can see the sum of row & column is in last line. Here we getting sailing club as 250 so answer will be 250/400.

26. dp says:

Option B

27. Kofi DL says:

B…

28. aryan says:

B

29. BSankar says:

30. BSankar says:

‘A’ could be answer if the question ask for “what is the probability that a student chosen at random is a member of the sailing club or both?”

Am I right GMAT team?

31. Nope !,

Saying “member of the sailing club or both” or “member of the sailing club” is basically same thing.

32. Nitin Sharma says:

B

33. Bruno says:

x-50+200-50+50=400
x=250

so, 250/400 or , 5/8, B!!!!