Marbles 1: Yellow

Probability Level 2

There are 35 marbles in a bag. Of which 3 are white, 5 are blue, 8 are red, 9 are green and 10 are yellow. The marbles will be taken out at random until a yellow marble is taken out.

What is the minimum number of many marbles needed to be taken out, to guarantee that we will get a yellow marble?


The answer is 26.

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Anthony Teo by Anthony Teo , 21, Netherlands

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1 solution

Parveen Soni
Nov 16, 2014

go for worst situation:- all other+1 yellow(think yourself) =26 if at most
1 if atleast

2 Helpful 0 Interesting 0 Brilliant 0 Confused

Don't you mean "at most" instead of "at least"? The way it's worded, I believe the answer is 1, since there is a chance the first marble will be yellow.

Jason Everetts - 6 years, 6 months ago

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I agree it should be 1 and 26 for the worst case scenario.

Angelo Campomanes - 6 years, 6 months ago

Thanks. Those who previously answered 1 have been marked correct.

In future, if you spot any errors with a problem, you can “report” it by selecting the “dot dot dot” menu in the lower right corner. You will get a more timely response that way.

Calvin Lin Staff - 6 years, 6 months ago

if this is what is required, the question should have been 'at most' not 'at least'

Umang Agarwal - 6 years, 6 months ago

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Thanks for the suggestion I did not realize that. I will edit the wording.

Anthony Teo - 6 years, 6 months ago

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