Simple probability that one or two are left-handed

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waxydock

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Aug 22, 2006
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Here is the question, and the answer follows. Could someone please explain to me how to do it. Thanks :)

A group of eleven students is independently selected. If the probability any given student is left-handed is 0.1, the probability of one or two of the group being left-handed is closest to...?

ANSWER: 0.9872
 
the answer is rounded, so the actual answer would have more decimal places i guess. Also this was a multiple choice question, with other answers close to this one.

But i was told 0.9872 was the right answer, but i dont know how to get it.
 
waxydock said:
i was told 0.9872 was the right answer, but i dont know how to get it.
Click to expand...
[combin(11,1)(0.1)<SUP>1</SUP>(0.9)<SUP>10</SUP>]+[combin(11,2)(0.1)<SUP>2</SUP>(0.9)<SUP>9</SUP>]=0.5966

If you stop and think about it, that given answer is just unreasonably high.
 
Thanks for clearing that up Pka. Thought I was going to have to go through all that stuff again!
 
opps, i made a mistake, below is the full set of answers and you guys are right, the given answer is (a) 0.5966. Im real sorry for giving the wrong answer, i must have mixed up the answers when i wrote it down.

Thanks again. :)


(a) 0.5966 (b) 0.7361 (c) 0.3026 (d) 0.1937 (e) 0.9872
 
No problem. If you get stuck again, just make another post.

This time with the right answers :p
 
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