BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Probability

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 23
Joined: Mon Feb 08, 2010 8:19 am
Location: Norway
Thanked: 1 times

Probability

by C » Tue Apr 13, 2010 11:00 pm
A florist has 2 azaleas, 3 buttercups, and 4 petunias. She puts two flowers together at random in a bouquet. However, the customer calls and says she does not want two of the same flower. What is the probability that the florist does not have to change the bouquet?

OA is [spoiler]13/18[/spoiler]

Source is MGMAT Word Translations, answer choices were not given. I did not understand the explanation, can someone please solve and explain?

Thanks
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 am
Thanked: 137 times
Followed by:5 members

by thephoenix » Tue Apr 13, 2010 11:58 pm
What is the probability that the florist does not have to change the bouquet? ---->MEANS THE florist has kpt two diff flowers
so we need to find the probability of keeping two diff flowers in the bouquet
which is same as 1- probability of keeping two same flowers in the bouquet
probability of keeping two same flowers in the bouquet=(2C2+3C2+4C2)/9C2=10/36
REQD PROBABILITY=1-10/36=26/36=13/18
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 208
Joined: Sun Sep 28, 2008 12:30 pm
Thanked: 22 times

by neoreaves » Wed Apr 14, 2010 12:17 am
2A, 3B, 4P

Total = 9

Probability of picking both A = 2/9 x 1/8
Probability of picking both B = 3/9 x 2/8
Probability of picking both P = 4/9 x 3/8

Probability of picking same = 2/9 x 1/8 + 3/9 x 2/8 + 4/9 x 3/8 = 20/72

Probability she wont have to change the flowers = Probability of not picking same = 1 - 20/72 = 13/18
Top
Post new topic Post Reply
• Page 1 of 1