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solution to jelly beans problem By kollol on Sunday, August 20, 2006 (UMST)

four Reply to this Comment

mmm... beans By gryyn on Monday, February 05, 2007 (UMST)

The maximum amount of grabs needed is two grabs. At the first time, you either get two similar beans (problem solved) or you get two beans with different colours. Now during the next grab you can get two similar beans (problem solver) or you get a colour you didnt have before and a colour you already had. Since there is no fourth colour the second bean on the second pick has to be the colour you already have. Reply to this Comment

solve by probability By nguyen_a on Saturday, May 05, 2007 (UMST)

Well, if the beans are placed into the bucket one layer at a time then it takes 1 draw to have 2 beans of the same of color.  But assuming that the beans are evenly distributed, then let n = number of beans of a color, m = total number of beans in the bucket, the probability of getting 2 beans of same color is: (n * (n-1) ) / (m * (m-1)) Now, plug in an example: n = 3 beans of a color, m = 10 total number of beans, the probability of getting 2 beans of same color is= 3*2 / 10*9 = 6/90 or 1/15.  So 15 draws are needed. Reply to this Comment

question By SantiagoICanepa on Friday, May 25, 2007 (UMST)

How do you know you pick two of a like color if the eyes are closed? Reply to this Comment

4 By markz on Wednesday, June 06, 2007 (UMST)

i concur. 4 is the answer. Worst case is 3 beans pulled at random will be red, blue and green. At this point forth bean will make a pair with one of the three. Reply to this Comment

4 jelly beans By monty on Sunday, September 16, 2007 (UMST)

worst case... you might pick red then blue then green in 3 attempts... in the 4th attempt you will pick any of the 3 (R/G/B) jelly bean... so you will get a pair of like coloured jelly bean! therefore 4 attempts are required... Reply to this Comment

correct By vinodhsen on Monday, November 19, 2007 (UMST)

Hi All,   this is the correct one .   regards vinodhsen Reply to this Comment

it's four either way, but... By insidi0us on Monday, May 19, 2008 (UMST)

isn't the question asking: "how many jelly beans must you grab in ONE ATTEMPT to be certain that two of them are of the same color?"? every answer i see here is interpreting the question as if it's asking "how many times must you draw one jelly bean before you can be certain you have two of the same color?" the answer would obviously be four, but i don't think the question is asking that. read it again: "how many do you have to grab to be sure you have 2 of the same?"... is simply asking how many do u need to pick up with ONE grab... if interpreting it this way, it would depend on how the jelly beans were distributed... if in layers, then just 2. if randomly, then four. if you never knew what the distribution looked like, and your eyes were closed, then the answer remains at four. Reply to this Comment

Answer By Cibert on Tuesday, July 08, 2008 (UMST)

Huuum If The Question its exactly like there, Then The answer is 4, But Maybe They are thinking about, how many jellys i need to grab to be sure of have 2 of the same LIKED jelly ???, If That I think the only way to be sure of that its to grab all of them =S. But If not 4 Its Ok. Reply to this Comment