It is currently 25 Sep 2017, 00:59

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

t1, t2, t3, t4...tn what is the value of n? 1) Sum of n

Author Message
TAGS:

Hide Tags

Intern
Joined: 21 Nov 2006
Posts: 44

Kudos [?]: 7 [0], given: 0

t1, t2, t3, t4...tn what is the value of n? 1) Sum of n [#permalink]

Show Tags

09 Jan 2007, 07:43
00:00

Difficulty:

35% (medium)

Question Stats:

75% (00:38) correct 25% (00:33) wrong based on 12 sessions

HideShow timer Statistics

t1, t2, t3, t4...tn what is the value of n?

1) Sum of n terms is 3,124

2) Mean of terms is 4

I got a 47 on the prep and these are the dumb ones I get wrong. How to proceed?

Thanks
Eric
[Reveal] Spoiler: OA

Kudos [?]: 7 [0], given: 0

SVP
Joined: 01 May 2006
Posts: 1794

Kudos [?]: 165 [0], given: 0

Show Tags

09 Jan 2007, 08:17
(C) for me

Stat 1
We could have any value for n.

o If n = 1, then Sum t(n) = 3,124 = t(1)
o If n = 100 as well as t(1) = 3,124 and t(k) = 0 with 1 < k <= n, Sum t(n) = 3,124

INSUFF.

Stat 2
Here again, we could have any value of n and get an averge of 4.

INSUFF.

Both (1) & (2)

The rule : Sum / n = av gives us the answer.

n = Sum / av = 3124 / 4 = 781.

SUFF.

Last edited by Fig on 09 Jan 2007, 08:50, edited 1 time in total.

Kudos [?]: 165 [0], given: 0

Intern
Joined: 21 Nov 2006
Posts: 44

Kudos [?]: 7 [0], given: 0

Show Tags

09 Jan 2007, 08:45
Thanks. Looks awfully easy now. Number sequences are hard for me. Not sure why. The math behind them is pretty easy.

Eric

Kudos [?]: 7 [0], given: 0

SVP
Joined: 01 May 2006
Posts: 1794

Kudos [?]: 165 [0], given: 0

Show Tags

09 Jan 2007, 08:54
Yes .... Usually, the used operands are + or - and *. So we are never so far in the concept of number sequence for the GMAT. ... Pretty good news

I think it's a question of practice to carck and to feel confortable with these questions

ericttz wrote:
Thanks. Looks awfully easy now. Number sequences are hard for me. Not sure why. The math behind them is pretty easy.

Eric

Kudos [?]: 165 [0], given: 0

Director
Affiliations: FRM Charter holder
Joined: 02 Dec 2006
Posts: 727

Kudos [?]: 94 [0], given: 4

Schools: Stanford, Chicago Booth, Babson College

Show Tags

09 Jan 2007, 09:29
Fig wrote:
(C) for me

Stat 1
We could have any value for n.

o If n = 1, then Sum t(n) = 3,124 = t(1)
o If n = 100 as well as t(1) = 3,124 and t(k) = 0 with 1 < k <= n, Sum t(n) = 3,124

INSUFF.

Stat 2
Here again, we could have any value of n and get an averge of 4.

INSUFF.

Both (1) & (2)

The rule : Sum / n = av gives us the answer.

n = Sum / av = 3124 / 4 = 781.

SUFF.

Hi Fig,

can we assume that it is Arithmetic progression?

Kudos [?]: 94 [0], given: 4

SVP
Joined: 01 May 2006
Posts: 1794

Kudos [?]: 165 [0], given: 0

Show Tags

09 Jan 2007, 09:35
aurobindo wrote:
Fig wrote:
(C) for me

Stat 1
We could have any value for n.

o If n = 1, then Sum t(n) = 3,124 = t(1)
o If n = 100 as well as t(1) = 3,124 and t(k) = 0 with 1 < k <= n, Sum t(n) = 3,124

INSUFF.

Stat 2
Here again, we could have any value of n and get an averge of 4.

INSUFF.

Both (1) & (2)

The rule : Sum / n = av gives us the answer.

n = Sum / av = 3124 / 4 = 781.

SUFF.

Hi Fig,

can we assume that it is Arithmetic progression?

No. We are never allowed to assume something that restricts the original problems . We must remain general if the problem is general

It could be any kind of sequences here .

o t(n) = t(n-1) + 1
o t(n) = t(n-1)
o t(n) = 2*t(n-1)
o t(n) = 1/t(n-1)

Kudos [?]: 165 [0], given: 0

Director
Affiliations: FRM Charter holder
Joined: 02 Dec 2006
Posts: 727

Kudos [?]: 94 [0], given: 4

Schools: Stanford, Chicago Booth, Babson College

Show Tags

09 Jan 2007, 10:25
Fig wrote:
aurobindo wrote:
Fig wrote:
(C) for me

Stat 1
We could have any value for n.

o If n = 1, then Sum t(n) = 3,124 = t(1)
o If n = 100 as well as t(1) = 3,124 and t(k) = 0 with 1 < k <= n, Sum t(n) = 3,124

INSUFF.

Stat 2
Here again, we could have any value of n and get an averge of 4.

INSUFF.

Both (1) & (2)

The rule : Sum / n = av gives us the answer.

n = Sum / av = 3124 / 4 = 781.

SUFF.

Hi Fig,

can we assume that it is Arithmetic progression?

No. We are never allowed to assume something that restricts the original problems . We must remain general if the problem is general

It could be any kind of sequences here .

o t(n) = t(n-1) + 1
o t(n) = t(n-1)
o t(n) = 2*t(n-1)
o t(n) = 1/t(n-1)

Thanks Fig. Now I understand ur logic

Kudos [?]: 94 [0], given: 4

Manager
Joined: 17 Mar 2010
Posts: 180

Kudos [?]: 209 [0], given: 9

Show Tags

10 Oct 2010, 22:59
If the terms of sequance are t1, t2, t3.... tn. What is the value of n?
1. The sum of n terms is 3124
2. The average of n terms is 4

Kudos [?]: 209 [0], given: 9

Retired Moderator
Joined: 02 Sep 2010
Posts: 794

Kudos [?]: 1156 [0], given: 25

Location: London

Show Tags

10 Oct 2010, 23:02
merging similar topics
_________________

Kudos [?]: 1156 [0], given: 25

Re: Series   [#permalink] 10 Oct 2010, 23:02
Display posts from previous: Sort by