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tinni
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 Posted: Wed Jul 04, 2007 9:56 am Post subject: PS - Probability |
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If an integer n is to be chosen at random from the integers 1 to 96, inclusive, what is the probability that n(n + 1)(n + 2) will be divisible by 8?
A. 1/4
B. 3/8
C. 1/2
D. 5/8
E. 3/4
OA , after couple of discussions. |
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gabriel
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| Posted: Wed Jul 04, 2007 10:27 am Post subject: Re: PS - Probability |
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| tinni wrote: | If an integer n is to be chosen at random from the integers 1 to 96, inclusive, what is the probability that n(n + 1)(n + 2) will be divisible by 8?
A. 1/4
B. 3/8
C. 1/2
D. 5/8
E. 3/4
OA , after couple of discussions. |
ok ... here goes .... in all n(n+1)(n+2) can have 96 different values ...
... for the condition given that n(n+1)(n+2) is divisible by 8 .. we can see that whenever n is a even number the function n(n+1)(n+2) is divisible by 8 ... also the function is divisible by 8 when (n+1) takes the value 8,16,24.... 96 ... so the total no. of values that the function is divisible by 8 is 48+12 = 60 .. so the probability is 60/96 = 5/8 ... so the answer is D ... |
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tinni
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| Posted: Wed Jul 04, 2007 10:48 am Post subject: Re: PS - Probability |
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Rock on !! Thank you.
I know where I went wrong. I haven't considered the (n+1) stuff, where we have 12 more numbers. |
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