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by chetanojha » Fri Aug 30, 2019 2:25 am
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Hi,

I got this question which I am finding hard to understand and solve.

"There are 15 yellow balls, 10 blue balls and 8 green balls mixed up in a bag. Paul takes the balls from the bag one by one at random. He wants to take out at least 2 balls of each colour.

What is the least number of balls that Paul needs to take from the bag to guarantee doing this?"


Also if somebody can explain me who to approach this question?


Thanks.
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by GMATGuruNY » Fri Aug 30, 2019 3:18 am
chetanojha wrote:Hi,

I got this question which I am finding hard to understand and solve.

"There are 15 yellow balls, 10 blue balls and 8 green balls mixed up in a bag. Paul takes the balls from the bag one by one at random. He wants to take out at least 2 balls of each colour.

What is the least number of balls that Paul needs to take from the bag to guarantee doing this?"


Also if somebody can explain me who to approach this question?


Thanks.
Check my solutions for the following problems:
https://www.beatthegmat.com/jellybeans-t89202.html
https://www.beatthegmat.com/have-23-ball ... 83542.html
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
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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].
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by Scott@TargetTestPrep » Wed Sep 04, 2019 5:16 pm
chetanojha wrote:Hi,

I got this question which I am finding hard to understand and solve.

"There are 15 yellow balls, 10 blue balls and 8 green balls mixed up in a bag. Paul takes the balls from the bag one by one at random. He wants to take out at least 2 balls of each colour.

What is the least number of balls that Paul needs to take from the bag to guarantee doing this?"


Also if somebody can explain me who to approach this question?


Thanks.
The worst case scenario is that he removes 25 balls and they are the 15 yellow balls and 10 blue balls. We see that he doesn’t have 2 balls of each color. However, if he removes 2 more balls, which must be green, he is now guaranteed to have at least two balls of each color. So he must remove a total of 27 balls.

Scott Woodbury-Stewart
Founder and CEO
[email protected]

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