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

Redeem

DS-Probability

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 89
Joined: Thu Aug 26, 2010 9:29 am
Thanked: 4 times

DS-Probability

by danjuma » Sat Nov 27, 2010 3:30 pm
A drawer contains 36 stocks and 2 stocks are selected at random without replacement. What is the probability that both socks are black?


1.The probability is 4/9 that the first sock is black.

2.The number of white socks in the drawer is 4 more than the number of black socks.
Top
Source: — Data Sufficiency |
Senior | Next Rank: 100 Posts
Posts: 65
Joined: Tue Nov 23, 2010 9:44 am
Thanked: 16 times
Followed by:6 members
GMAT Score:780

by Laura GMAT Tutor » Sat Nov 27, 2010 3:50 pm
Where did you find this question?
Last edited by Laura GMAT Tutor on Sat Nov 27, 2010 4:19 pm, edited 1 time in total.
follow me on twitter! :)
@LauraGMATtutor

or visit my blog:
https://realusefulgmat.blocked/
Top
User avatar
GMAT Instructor
Posts: 613
Joined: Thu Mar 22, 2007 6:17 am
Location: madrid
Thanked: 171 times
Followed by:64 members
GMAT Score:790

by kevincanspain » Sat Nov 27, 2010 4:04 pm
danjuma wrote:A drawer contains 36 stocks and 2 stocks are selected at random without replacement. What is the probability that both socks are black?


1.The probability is 4/9 that the first sock is black.

2.The number of white socks in the drawer is 4 more than the number of black socks.
Ask yourself what you need to know in order to answer the question: how many of the 36 socks are black?

(1) tells us that 4/9 of the 36 socks are black. SUFF
(2) tells us that there are at least 4 black socks. However, there may be socks that are neither black nor white NOT SUFF
Kevin Armstrong
GMAT Instructor
Gmatclasses
Madrid
Top
Post new topic Post Reply
• Page 1 of 1