GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Oct 2019, 16:12

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Although the games have already happened, a friend of mine had a bet

Author Message
TAGS:

### Hide Tags

Manager
Joined: 26 Oct 2010
Posts: 57

### Show Tags

04 Apr 2011, 23:38
00:00

Difficulty:

45% (medium)

Question Stats:

11% (01:01) correct 89% (01:17) wrong based on 27 sessions

### HideShow timer Statistics

Although the games have already happened, a friend of mine had a bet where he could win one of two ways from the final four.

1. VCU wins over Kansas
2. UCONN wins the whole tournament. (wins against UK, and then wins the final)

What's the probability of him winning the bet?

A. 1/2
B. 3/4
C. 5/8
D. 1/8
E. 1/4
Manager
Joined: 26 Oct 2010
Posts: 57

### Show Tags

04 Apr 2011, 23:39
I think the answer would be 5/8 1/2 (VCU) + 1/4( UCONN) - 1/2*1/4 (VCU and UCONN) = 5/8
Retired Moderator
Joined: 16 Nov 2010
Posts: 1246
Location: United States (IN)
Concentration: Strategy, Technology

### Show Tags

04 Apr 2011, 23:42
I'm getting 3/4.

1/2 (VCU wins over Kansas) + 1/2 (UCONN wins against UK)*1/2(UCONN wins the final) = 1/2 + 1/4 = 3/4

What is the OA ?
_________________
Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings
Manager
Joined: 11 Dec 2010
Posts: 102
WE: Consulting (Consulting)

### Show Tags

05 Apr 2011, 18:29
(1/2)*(1/2*1/2) = 3/4
GMAT Tutor
Joined: 24 Jun 2008
Posts: 1802

### Show Tags

05 Apr 2011, 20:44
1
jonblazon wrote:
Although the games have already happened, a friend of mine had a bet where he could win one of two ways from the final four.

1. VCU wins over Kansas
2. UCONN wins the whole tournament. (wins against UK, and then wins the final)

What's the probability of him winning the bet?

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

While 3/4 might be a tempting answer here, jonblazon's solution is actually correct, and the answer is 5/8. The problem with the other solutions is that they double-count when *both* VCU wins and when UCONN wins. He doesn't win the bet twice when that happens!

You can break down all of the possible events as follows:

VCU wins AND UConn wins it all: (1/2)*(1/4) = 1/8 --> he wins the bet
VCU wins AND UConn does not win it all: (1/2)*(3/4) = 3/8 --> he wins the bet
VCU loses AND UConn wins it all: (1/2)*(1/4) = 1/8 --> he wins the bet
VCU loses AND UConn does not win it all: (1/2)*(3/4) = 3/8 --> he does not win the bet

Adding you can see the answer should be 5/8, though jonblazon's solution is a more elegant approach.

Of course all of this assumes that each game is essentially like a coinflip, something which isn't true in real life, since it's not just luck that determines which team wins a basketball game.
_________________
GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com
Manager
Joined: 18 Jan 2011
Posts: 209

### Show Tags

10 Apr 2011, 00:38
# of different ways your friend can win the bet -
1) VCU wins while UConn loses semi-final = 1/2*1/2 = 1/4
2) VCU wins while UConn loses final = 1/2*1/2*1/2 = 1/8
3) VCU loses while UConn wins = 1/2*1/2*1/2 = 1/8
4) VCU wins and UConn wins = 1/2*1/2*1/2 = 1/8
1/4+1/8+1/8 +1/8= 5/8
_________________
Good Luck!!!

***Help and be helped!!!****
Non-Human User
Joined: 09 Sep 2013
Posts: 13382

### Show Tags

24 Jan 2019, 22:30
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Although the games have already happened, a friend of mine had a bet   [#permalink] 24 Jan 2019, 22:30
Display posts from previous: Sort by