prob. question

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jinniechoi

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this question is from topscore
three card from ordinary deck,
prob. of all three are black?
please explain...
thanks~!
 
well lets just say that you have 50 cards in a deck...so 25 black and 25 red

well the first black card is exactly 0.5 probability of it being black

second black card is 24 out of 49

third black card is 23 out of 48

well, each consecutive probability of picking a black card is roughly 1/2...although not quite

so we can assume the probability of getting three black card is slightly less than (1/2)^3

so the answer should be slightly lower than 0.125 or 12.5% I would venture to say that the answer is around 0.11 or 11% or something, btw what is the answer?

nice to see korean girls trying to enter the field of dentistry 😉
 
Is it just me or does topscore have a way that you review the actual questions that were on the exam? What good does it do you if you don't know why you got the question wrong.
 
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