Tricky PS

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 391
Joined: Sat Mar 02, 2013 5:13 am
Thanked: 50 times
Followed by:4 members

Tricky PS

by rakeshd347 » Sat Oct 19, 2013 7:55 pm
If a box contains 10 red pills, 5 blue pills, and 12 yellow pills, what is the least number of pills one must extract from the box to ensure that at least three pills of each color are among those extracted?
12
17
18
23
25

OA is E
Last edited by rakeshd347 on Sun Oct 20, 2013 1:33 am, edited 1 time in total.

User avatar
Legendary Member
Posts: 1556
Joined: Tue Aug 14, 2012 11:18 pm
Thanked: 448 times
Followed by:34 members
GMAT Score:650

by theCodeToGMAT » Sat Oct 19, 2013 8:14 pm
Considering worst case...
10 + 12 + 3 = 25

Answer [spoiler]{E}[/spoiler]?
Last edited by theCodeToGMAT on Mon Oct 21, 2013 6:44 am, edited 1 time in total.
R A H U L

User avatar
Master | Next Rank: 500 Posts
Posts: 490
Joined: Thu Jul 04, 2013 7:30 am
Location: Chennai, India
Thanked: 83 times
Followed by:5 members

by Uva@90 » Sat Oct 19, 2013 8:22 pm
Consider the worst case scenario where he removes 12 yellow pills(which contributes more) then 10 red pills then 3 blue pills.

i.e. 12+10+3 =25

SO Answer is E

Regards,
Uva.
Known is a drop Unknown is an Ocean

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

by [email protected] » Sat Oct 19, 2013 11:29 pm
Hi rakeshd347,

Uva@90 has described this type of question in a great way: the "worst case scenario." In questions that ask about what it would take to "ensure" or "guarantee" an outcome, you have to consider the "worst case scenario."

That "worst case scenario" here would be if you maximized the number of 2 colors before you got 3 of the final color:

12 yellows + 10 reds......+ 3 blues = 25

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Sun Oct 20, 2013 4:02 am
rakeshd347 wrote:If a box contains 10 red pills, 5 blue pills, and 12 yellow pills, what is the least number of pills one must extract from the box to ensure that at least three pills of each color are among those extracted?
12
17
18
23
25

OA is E
As noted above, this is a WORST-CASE SCENARIO problem.
To GUARANTEE that 3 of each color are chosen, we must determine the worst-case scenario: the greatest number of marbles that can be removed WITHOUT choosing at least 3 of each color.

If all of the yellow pills and all of the red pills are removed first, the number of pills removed = 12+10 = 22.
Since there are more yellow pills and red pills than blue pills, 22 is the maximum number of pills that can be removed without choosing at least 3 of each color.

To remove at least 3 of each color, 3 blue pills must now be chosen, yielding the following total:
22+3 = 25.

The correct answer is E.

Similar problems:
https://www.beatthegmat.com/jellybeans-t89202.html
https://www.beatthegmat.com/have-23-ball ... 83542.html
https://www.beatthegmat.com/d-j-started- ... 61213.html
https://www.beatthegmat.com/combinatorics-t266857.html
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

User avatar
Master | Next Rank: 500 Posts
Posts: 153
Joined: Mon Apr 11, 2011 7:13 am
Location: India
Thanked: 22 times
Followed by:7 members
GMAT Score:540

by sahilchaudhary » Mon Oct 21, 2013 6:43 am
We have to take the worst case.
12+10+3 = 25.

So, the answer is E.
Sahil Chaudhary
If you find this post helpful, please take a moment to click on the "Thank" icon.
https://www.sahilchaudhary007.blocked