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nikhilagrawal
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 Posted: Wed Jul 23, 2008 4:22 am Post subject: P and C |
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My name is AJEET. But my son accidentally types the name by interchanging a pair of letters in my name. What is the probability that despite this interchange, the name remains unchanged?
a) 5%
b) 10%
c) 20%
d) 25% |
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sudhir3127
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| Posted: Wed Jul 23, 2008 4:35 am Post subject: |
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My answer is 10 %
2/20= 10% |
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reachac
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| Posted: Wed Jul 23, 2008 5:29 am Post subject: |
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| 10% |
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nikhilagrawal
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| Posted: Wed Jul 23, 2008 5:53 am Post subject: |
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can some one help me in determing the no of successful events.
I amy confused how we are getting 20 .. pls explain .. |
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acecoolan
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| Posted: Wed Jul 23, 2008 6:44 pm Post subject: |
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Can someone explain this ....my Probability and Perm/Comb fundaes are totally 0 ..I think
Can anyone also suggest where to start afresh on these topics? |
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Stuart Kovinsky
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| Posted: Wed Jul 23, 2008 8:30 pm Post subject: Re: P and C |
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| nikhilagrawal wrote: | My name is AJEET. But my son accidentally types the name by interchanging a pair of letters in my name. What is the probability that despite this interchange, the name remains unchanged?
a) 5%
b) 10%
c) 20%
d) 25% |
There are 5C2 different pairs of letters in your name.
5C2 = 5!/2!3! = 5*4/2 = 10
So, there are 10 swaps that your son could make.
Only 1 of those swaps (E/E) would leave your name spelled correctly. So, there's a 1/10 chance that your name will still be fine: choose (b).
Just curious, why aren't there 5 answer choices?
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