Plz help bit confused

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Plz help bit confused

by golu23 » Tue Jan 03, 2012 5:08 am
4)IS THE POSITIVE INTEGER N odd
a)N=2K+1
B)2n+1 i

5)If N is product of least and greatest of 6 consecutive integers n=?
a)THE GREATEST CONS INT IS 20
B)THE AVG OF 6 CONS INT IS 17.5
Source: — Data Sufficiency |

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by neelgandham » Tue Jan 03, 2012 5:28 am
5)
If n is product of least and greatest of 6 consecutive integers n=?
1. The greatest of the consecutive integers is 20
Let a-2, a-1, a,a+1, a+2, a+3 be the 6 consecutive integers, where a-2 is the least and a+3 is the greatest. Statement 1 says a+3 = 20, then the least valued integer a-2 = 15
n = (a+3)*(a-2) = 20*15. Sufficient!
2 .The average of the 6 consecutive integers is 17.5
Let a-2, a-1, a,a+1, a+2, a+3 be the 6 consecutive integers, where a-2 is the least and a+3 is the greatest. Statement 2 says a-2 + a-1 + a + a+1 + a+2 + a+3 = 17.5 * 6. Implies 6a + 3 = 105, a = 17.
n = (a+3)*(a-2) = 20*15 Sufficient!

Hence Answer D
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by shankar.ashwin » Tue Jan 03, 2012 5:29 am
golu23 wrote: 5)If N is product of least and greatest of 6 consecutive integers n=?
a)THE GREATEST CONS INT IS 20
B)THE AVG OF 6 CONS INT IS 17.5
Statement 1

Greatest = 20, therefore least = 15 - Sufficient

Statement 2

Avg = 17.5

17.5 is the average between 17 & 18, now complete the 6 numbers -- (15-20) - Sufficient

D

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by neelgandham » Tue Jan 03, 2012 5:31 am
4)IS THE POSITIVE INTEGER N odd
1)N=2K+1
2)2n+1 i

1) N = 2k+1 = Even + Odd = Odd Sufficient!
2) No clue what it is. Can you please provide the complete question ?
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by LalaB » Tue Jan 03, 2012 11:22 am
4)IS THE POSITIVE INTEGER N odd
a)N=2K+1 means N=even+odd, so N is odd.(bingo)
B)2n+1 nothing is mentioned about n itself.so, insuff

answ is A

5)If N is product of least and greatest of 6 consecutive integers n=?
a)THE GREATEST CONS INT IS 20
B)THE AVG OF 6 CONS INT IS 17.5

since it is a DS q, no need to solve it mathematically( huge sigh :) )

so, we've got that our set consists of 6 consecutive integers, and N =Least*Greatest =?

a)THE GREATEST CONS INT IS 20. it means, that we have already Greatest num. now need to find the least one.since we are told,that integers are cons, we can count 5 cons.integers back to find the least one (though do not do it. it is just a DS q. :) ) so A is suff

B)THE AVG OF 6 CONS INT IS 17.5 means u already know the median of the set (since mean=median in a cons set)
knowing it u can count back and forward to find our greatest and least numbers(again, do not do it :) )

so, ans is D

hope it helps

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by santhoshsram » Wed Jan 04, 2012 8:35 am
4)IS THE POSITIVE INTEGER N odd
a)N=2K+1
B)2n+1 i

(B) obviously seems incomplete. Can we get the complete Statement (B) please.

(A) The question says that N is an integer, but nothing about K itself.

If K is an integer then 2K + 1 is always ODD. But it is not mentioned that K is an integer.

If K = 1.5, N = 2*1.5 + 1 = 4 => Even
If K = 2, N = 2*2 + 1 = 5 => ODD

Not sufficient.

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by golu23 » Thu Jan 05, 2012 5:57 pm
@Santosh it is the complete statement i've posted as it is.This is Question frm gmatprep.

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by [email protected] » Sat Jan 21, 2012 5:02 am
4)IS THE POSITIVE INTEGER N odd
a)N=2K+1
B)2n+1 i

(B) obviously seems incomplete. Can we get the complete Statement (B) please.

(A) The question says that N is an integer, but nothing about K itself.

If K is an integer then 2K + 1 is always ODD. But it is not mentioned that K is an integer.

If K = 1.5, N = 2*1.5 + 1 = 4 => Even
If K = 2, N = 2*2 + 1 = 5 => ODD

Not sufficient.



Santosh, the question clearly says that n is positive integer. so n cannot be a fraction or any negative value. Hence the answer is clearly A... as Statement B is not given properly...
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by shekhar.kataria » Sat Jan 21, 2012 11:04 am
A is Not Suffiecient
Reason : K can be a fraction say,K = 3/2 which gives N as even

Correct me if i m wrong.
neelgandham wrote:4)IS THE POSITIVE INTEGER N odd
1)N=2K+1
2)2n+1 i

1) N = 2k+1 = Even + Odd = Odd Sufficient!
2) No clue what it is. Can you please provide the complete question ?
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