[Laminar]

You have 500 jellybeans in a single container. Five different colors, 100 of each color.

You're blindfolded.

What is the minimum number of jellybeans you need to pull out so that you are guaranteed to have 5 of a single color?

[The Final Dakar]

496?

Edit: Bwahaha, I read that as 100 of a single color. Where the hell did I get that from.

[BadKosh]

25?

[Snow-i]

Guaranteed?

I believe 496 is the answer.

Edit: Made the same mistake as dark....Hahaha. Okay. Naptime!
Edit 2: Dakar.....about that nap....

[Laminar]

It's from a brain teaser book. I disagree with the answer given, but there's no explanation.

[The Final Dakar]

Originally Posted by Snow-i 

Edit: Made the same mistake as dark....Hahaha.

I spy another mistake.

[Snow-i]

Well, if you had 4 of every color you'd have 20, so 21 to make one of the colors 5?

[Laminar]

Yes, 21 is correct. It appears as if I tried to say that 4*4 = 20, and that's why I wasn't getting it.

[Snow-i]

So how many would you need to pull out to make sure that you are guaranteed 5 of a single color left in the jar?
None. They are all already in the jar

[subego]

21, but that's too easy.

Edit: beat while mulling it over.

[andi*pandi]

I would have guessed 5, since it's possible.

[turtle777]

Originally Posted by andi*pandi 

I would have guessed 5, since it's possible.

Possible != guaranteed.

-t

[BadKosh]

5 colors. you could have 4 of each * 5 = 20 and one more would be 21.


revised answer - 21

[olePigeon]

Wait, does guarantee mean 100% probability? Although highly unlikely, you could pull 400 jelly beans of only the first 4 colors. You would need at least 401 jelly beans to guarantee at least 1 of each color.

[turtle777]

Originally Posted by olePigeon 

401, I think. Although highly improbable, you could pull 400 jellybeans of only the first 4 colors, and not any of the 5th. If you pull 401, you're guaranteed to get at least one of each color.

You misunderstood the question.

How many jelly beans do you have to draw blindly to get at least 5 of one color (not 5 of ALL colors).
Obviously, after drawing 20, you will have (worst case) 4 of each color.
So 20+1 will guarantee the 5th bean that will give you 5 of one color.

Most likely, you will have hit 5 of one color before drawing 20.

-t

[olePigeon]

Oops, I misread it. I thought it was 1 of each color.

[bstone]

42 is the answer

[Oisín]

Originally Posted by Snow-i 

So how many would you need to pull out to make sure that you are guaranteed 5 of a single color left in the jar?
None. They are all already in the jar

Well, that’s a bit too easy: one.

Edit: Actually, no, it’s not too easy, ’cause it doesn’t say whether or not you have to pull any out at all; so the answer could be zero, too.

Double-edit: Oh. White text. Meh.

[CreepDogg]

Hm. When I read the question, I thought it to mean the number that would guarantee 5 of a particular color. In which case I think the answer is 405 (as others have pointed out, although improbable, you could pull all of the other 4 colors before you pull any of your particular color).

But yeah - it seems everyone else has ready it to guarantee 5 of any color. Big difference. And when in doubt, 42 always works!

[Eug]

Heh. I was thinking 405 too. Misread the question I guess. It seems the biggest brain teaser here is just reading the question right.

Originally Posted by turtle777 

Possible != guaranteed.

Option = on a Mac. ≠

[turtle777]

Originally Posted by Eug 

Option = on a Mac. ≠

I'm on my iPad.

-t

[Ghoser777]

This is an application of the Pigeonhole Principle.

Assume the colors are red, blue, green, yellow, and orange).

In the worst case, if you take out 20, then you can have 4 reds, 4 blues, 4 greens, 4 yellows, and 4 oranges (so no 5 of a kind). But on the next choice, you will end up with a 5th color in any category.

Therefore, the answer is 21 (like others have explained above).

[The Final Dakar]

Math makes me drink. To do that legally, you have to be 21.

So therefore, the answer is 21.

[Laminar]

Best explanation yet.

[Oisín]

Originally Posted by The Final Dakar 

Math makes me drink. To do that legally, you have to be 21.

So therefore, the answer is 21.

This solution makes my head hurt.

So for you, the answer is 21; for me, the answer is 15 (for low-percentage beverages) or 18 (for high-percentage beverages); and for a practicing Muslim, the answer is never/infinity?

That’s the toughest brain teaser ever.

[Buckaroo]

I'm thinking 405

Oops, I read it as 5 of each color, but now I realize that it reads one of each color, so I change my answer to 401.

I guess I read it wrong again. Five of a single color? hmmm. My answer would then be . . . I think 21. I'll have to think about it for a minute.

[Sealobo]

Snap!

[Sealobo]

"guaranteed" is the keyword.

[Sealobo]

assume ALL the color REALLY hates your guts and it just wouldn't let you draw 5 unless all other possible options are exhausted.

so it's 21

[ort888]

Four?

[Spheric Harlot]

Five, if you're Chuck Norris.

[andi*pandi]

Chuck Norris and I agree then.