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

It is currently 06 Dec 2019, 05:28

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

In a jar, 9 balls are white and the rest are red. If two balls are to

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59574
In a jar, 9 balls are white and the rest are red. If two balls are to  [#permalink]

Show Tags

New post 02 Oct 2018, 02:34
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

78% (02:52) correct 22% (01:52) wrong based on 41 sessions

HideShow timer Statistics

Manager
Manager
avatar
S
Joined: 21 Nov 2016
Posts: 71
GMAT 1: 640 Q47 V31
Re: In a jar, 9 balls are white and the rest are red. If two balls are to  [#permalink]

Show Tags

New post 02 Oct 2018, 03:44
2
The jar has 9 white balls, and the rest are red balls.
So, let total balls = t
The probability of picking 2 white balls without replacement is = 6/11
So, (9/t)x(8/t-1) = 6/11
on simplifying the above equation we would get a quadratic equation of the form,
t^2-t-132=0
Further simplifying we would get,
(t-12)(t+11)=0
Implies, t = 12, or t = -11
Since the no. of balls is supposed to be a positive integer, so t =12
So, the correct answer is C.
GMAT Club Bot
Re: In a jar, 9 balls are white and the rest are red. If two balls are to   [#permalink] 02 Oct 2018, 03:44
Display posts from previous: Sort by

In a jar, 9 balls are white and the rest are red. If two balls are to

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne