Braingle: 'Bag of Balls' Brain Teaser

Bag of Balls

Probability puzzles require you to weigh all the possibilities and pick the most likely outcome.

Puzzle ID:	#28618
Fun:	(2.31)
Difficulty:	(1.64)
Category:	Probability
Submitted By:	npf2005

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

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Comments

cms271828 Feb 14, 2006	Nice easy one, you would have to take out all 56 non-reds first, then the 3 reds
ben2 Feb 15, 2006	good and easy, my favorite kind
keveffect1 Feb 21, 2006	Way too easy and color is spelled as seen not colour (Unless your British I guess)
npf2005 Feb 22, 2006	im british. to be exact english
yellasubmrn Feb 25, 2006	Sorry but it was a little bit too easy. Nice, though.
npf2005 Feb 26, 2006	i cant submit any hard teasers. im too dumb to make them up lol
Lui312 Mar 01, 2006	wow pretty good
thompson1 Mar 10, 2006	this was really good . the only problem is i STILLdont get it!!
Methlos Mar 12, 2006	colour is the best way of spellling colour
jntrcs Mar 15, 2006	colour color who cares. i enjoyed the puzzle easy enough to get yet fun.
calmsavior Apr 12, 2006	thats the worstcase scenario
jax_the_ax Apr 13, 2006	DUMB
npf2005 Apr 13, 2006	what?
udoboy May 26, 2006	This question has nothing to do with probability.
mmmcla01 Jun 30, 2006	udoboy...I totally agree...how is this probability?
Dedrik Aug 09, 2006	you are looking for a probability of 100% if you want a harder version how many does he need to get a 42% chance of having 3 reds
masquerademe235 Sep 26, 2007	very nice and very tricky!!
spinnercat Oct 01, 2007	wrong category, but good teaser.
jsdodgers Apr 03, 2008	WAAAYY too easy. You must be VERY unlucky to take that many picks though.
javaguru Dec 22, 2008	And probability figures into this how? Maybe if you wanted to know that there is a 8C2 / 64C58 = 28/74974368 = 1/2677656 (approx. 0.000000373) probability of having to pick 59 balls before getting three red balls. But as stated, this is neither a probability teaser nor an interesting teaser.