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What is the value of the integer n? (1) N!= (N-1)!*N (2)

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What is the value of the integer n? (1) N!= (N-1)!*N (2)  [#permalink]

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New post 06 Jun 2011, 10:39
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

81% (01:02) correct 19% (01:31) wrong based on 73 sessions

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What is the value of the integer n?

(1) N!= (N-1)!*N

(2) N^3+3N^2+2N is divisible by 3

OPEN DISCUSSION OF THIS QUESTION IS HERE: what-is-the-value-of-the-integer-n-126638.html

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Re: What is the value of the integer n? (1) N!= (N-1)!*N (2)  [#permalink]

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New post 06 Jun 2011, 12:36
1
St 1 doesnt provide any information. Its just another way of expressing N!.

St 2 - solving the equation we get N (N+1) (N+2) is divisible by 3. N can have lot of values like 4,5,6,7.. etc.
so not sufficient.

together also we dont get a unique value of N.

So E.

I am not sure if this is GMAT Q. Does Gmat provide a sufficiency statement like 1? What is the source of the Q.
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Re: What is the value of the integer n? (1) N!= (N-1)!*N (2)  [#permalink]

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New post 06 Jun 2011, 14:24
it's taken from manhattan archive- which includes some of the hardest i have seen and frankly i believe that only som GC legends will be able to solve some of them under 4 minutes.

by the way, how do you decide to prefer E (which is correct) and not C
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Re: What is the value of the integer n? (1) N!= (N-1)!*N (2)  [#permalink]

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New post 06 Jun 2011, 14:39
1/ N! = N(N-1)(N-2).... = N[(N-1)(N-2)....] = N*(N-1)! so there is no new info brought by this by 1/. It is just another expression of N!

2/ N^3+3N^2+2N is divisible by 3: You can find endless integers fulfilling this condition.

--> The answer is E
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Re: What is the value of the integer n? (1) N!= (N-1)!*N (2)  [#permalink]

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New post 06 Jun 2011, 14:59
1
dimri10 wrote:
it's taken from manhattan archive- which includes some of the hardest i have seen and frankly i believe that only som GC legends will be able to solve some of them under 4 minutes.

by the way, how do you decide to prefer E (which is correct) and not C


Vow, MGMAT? i guess than must be to trick people.

Basically, if you combine A and B, there is no additional info other than what we have achieved in B. Because remember that A doesn't provide any other info other than its just different way of expressng N!.
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Re: What is the value of the integer n? (1) N!= (N-1)!*N (2)  [#permalink]

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New post 03 Dec 2017, 02:17
What is the value of the integer n?

(1) n!=n*(n – 1)! --> n*(n – 1)! equals to n! itself, so we have n!=n!. Useless statement.

(2) n^3 + 3n^2 + 2n is divisible by 3 --> n(n^2+3n+2)=n(n+1)(n+2): we have the product of 3 consecutive integers, which is ALWAYS divisible by 3. Useless statement.

(1)+(2) Two useless statements. Not sufficient.

Answer: E.

OPEN DISCUSSION OF THIS QUESTION IS HERE: what-is-the-value-of-the-integer-n-126638.html

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Re: What is the value of the integer n? (1) N!= (N-1)!*N (2) &nbs [#permalink] 03 Dec 2017, 02:17
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