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official guide 11th. PS #201 [#permalink ]
17 Feb 2009, 18:19

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i. n is an even number ii. n is an odd number iii. the average(arithmetic mean) of the n integers is 0 201. If the sum of n consecutive integers is 0, which of the following must be true? (A)i only (B)ii only (C)iii only (D)i and iii (E)ii and iii plz help me to understand. I already looked up the answer key, but i could not understand how to figure it out..

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Re: official guide 11th. PS #201 [#permalink ]
17 Feb 2009, 19:57

emily0506 wrote:

i. n is an even number ii. n is an odd number iii. the average(arithmetic mean) of the n integers is 0 201. If the sum of n consecutive integers is 0, which of the following must be true? (A)i only (B)ii only (C)iii only (D)i and iii (E)ii and iii plz help me to understand. I already looked up the answer key, but i could not understand how to figure it out..

e.g

-1,0,1 --> n=3 is odd and avg=0

0 --> n=1 is odd

n must be odd to make the sum of consecuting integers zero.

(ii) sume even number of consecutive integers, neverb to zero.

avg = sum of integers/number of integers = 0/n=0

(ii) and (iii) MUST BE TRUE

C.

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Re: official guide 11th. PS #201 [#permalink ]
17 Feb 2009, 22:39

i. n is an even number ii. n is an odd number iii. the average(arithmetic mean) of the n integers is 0 i. - the sum can never be 0 ii. - it might, or might not be: -1,0,1 or 2,3,4 iii. - will always be true, so the answer is C.

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Re: official guide 11th. PS #201 [#permalink ]
17 Feb 2009, 23:01

peraspera wrote:

i. n is an even number ii. n is an odd number iii. the average(arithmetic mean) of the n integers is 0 i. - the sum can never be 0 ii. - it might, or might not be: -1,0,1 or 2,3,4 iii. - will always be true, so the answer is C.

sum of 2,3,4 -- never be zero.. so .. this is ruled out.

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Re: official guide 11th. PS #201 [#permalink ]
18 Feb 2009, 10:32

x2suresh wrote:

peraspera wrote:

i. n is an even number ii. n is an odd number iii. the average(arithmetic mean) of the n integers is 0 i. - the sum can never be 0 ii. - it might, or might not be: -1,0,1 or 2,3,4 iii. - will always be true, so the answer is C.

sum of 2,3,4 -- never be zero.. so .. this is ruled out.

Exactly, that's why the answer is C.

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Re: official guide 11th. PS #201 [#permalink ]
18 Feb 2009, 10:36

peraspera wrote:

x2suresh wrote:

peraspera wrote:

i. n is an even number ii. n is an odd number iii. the average(arithmetic mean) of the n integers is 0 i. - the sum can never be 0 ii. - it might, or might not be: -1,0,1 or 2,3,4 iii. - will always be true, so the answer is C.

sum of 2,3,4 -- never be zero.. so .. this is ruled out.

Exactly, that's why the answer is C.

Sorry!! I overlooked..(sleepy...sleepy) it

thought E was only (III)

Updated Answer in my orignal post.

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Re: official guide 11th. PS #201 [#permalink ]
20 Feb 2009, 14:04

Whats going on here? Isnt the answer E? The Q says if the sum of n consecutive integers is 0, So even though 2,3,4 are consecutive, they don't qualify for this Q

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Re: official guide 11th. PS #201 [#permalink ]
24 Mar 2009, 04:10

Yeah, the answer should be E

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Re: official guide 11th. PS #201 [#permalink ]
24 Mar 2009, 14:30

icandy wrote:

Whats going on here? Isnt the answer E? The Q says if the sum of n consecutive integers is 0, So even though 2,3,4 are consecutive, they don't qualify for this Q

Yes, it is E.

Don't know what was there - maybe the original question got updated.

It should be E, as it it reads now.

Re: official guide 11th. PS #201
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24 Mar 2009, 14:30