Probability

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BTGmoderatorRO: Moderator; Posts: 772; Joined: Wed Aug 30, 2017 6:29 pm; Followed by:6 members

Probability

by BTGmoderatorRO » Fri Dec 29, 2017 4:50 am

There are 12 red balls, 10 blue balls, 15 green balls and 9 black balls in a bag. What is the minimum number of balls to be taken out of the bag to assure that you have all the balls of one color?

A. 10
B. 23
C. 43
D. 40
E. 16

OA is C

What is the easiest approach to solving this question? Pls, i need the help of an Expert.Thanks

Quote

Source: Beat The GMAT — Problem Solving | Fri Dec 29, 2017 4:50 am

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8083; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Mon Sep 02, 2019 6:37 pm

BTGmoderatorRO wrote:There are 12 red balls, 10 blue balls, 15 green balls and 9 black balls in a bag. What is the minimum number of balls to be taken out of the bag to assure that you have all the balls of one color?

A. 10
B. 23
C. 43
D. 40
E. 16

OA is C

What is the easiest approach to solving this question? Pls, i need the help of an Expert.Thanks

The worst case scenario is that we take out 14 green balls, 11 red balls, 9 blue balls and 8 black balls. We see that we still don't have all the balls of one color. However, if we take out one more ball, no matter what color it is, we will have all the balls of one color. Therefore, the total number of balls need to be taken out is 14 + 11 + 9 + 8 + 1 = 43.

Answer: C

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