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 Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

There is an finite number of elements in a sequence. What is [#permalink]
26 Nov 2005, 06:38

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct
0% (00:00) wrong based on 0 sessions

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

13. There is an finite number of elements in a sequence. What is the sum of all the elements in that sequence?

(1) There are negative numbers to correspond with all positive numbers in that sequence with the same absolute value.
(2) The number of positive and negative elements is the same. _________________

Auge um Auge, Zahn um Zahn !

Last edited by gamjatang on 30 Nov 2005, 23:28, edited 1 time in total.

"there are negative numbers to correspond with all positive numbers" doesnt mean that all neg. numbers correspond with all pos n unless the number of elements is the same _________________

If your mind can conceive it and your heart can believe it, have faith that you can achieve it.

"there are negative numbers to correspond with all positive numbers" doesnt mean that all neg. numbers correspond with all pos n unless the number of elements is the same

Wow.. you're right ..
we just tend to assume that it is the same case other way round as well that for every negative no there is a positive no

Both (1) and (2) are sufficient. sum of n-terms in the sequence= middle value * n.
1) is insufficient. if n-number of terms is even, average is 0, then n+(n-1)+(n-2).....+=0. e.g. -5; -3; -1; 1; 3; 5 However, if n-odd, e.g -5; -3; -1; 1; 3; 5; 7=1. Middle number can have any value depending on the sequence, if n is odd.

2) also insufficient, middle value can'be found from the information given.

Cobining both statements will suffice, since n is even and -ve and +ve numbers correspond, n+(n-1)+(n-2)....=0 _________________

(1)baiscally says that for all positive numbers there is an equal and positive negative number, however we dont know that for every negative number there is an equal positive number...insuff

(2) is also insufficient, there are equal number of negative numbers and given that we dont know the exact value of the numbers...

together, we still dont know the exact values of the negative numbers
say for example...

sequence is
-3, -2, -1, 2, 1, 1, so as you can see we have a repeat of positive number and we have an equal value negative number....the sum is -2....

sequence can also be
-3, -2, 2, 3...in this case the sum is 0...

(1)baiscally says that for all positive numbers there is an equal and positive negative number, however we dont know that for every negative number there is an equal positive number...insuff

(2) is also insufficient, there are equal number of negative numbers and given that we dont know the exact value of the numbers...

together, we still dont know the exact values of the negative numbers say for example...

sequence is -3, -2, -1, 2, 1, 1, so as you can see we have a repeat of positive number and we have an equal value negative number....the sum is -2....

sequence can also be -3, -2, 2, 3...in this case the sum is 0...

Well, yeah. But -3, -2, -1, 2, 1, 1 is not an algebraic sequence because the difference between the terms is not always the same. Am I right? _________________

Hmmm I believe that a sequence is basically a set where the order of elements is defined. In other words a, b, c is a different sequence of a, c, b. However a sequence doesn't have to have a certain formula for you to be able to derive each element. It doesn't even need to be monotonically increasing or decreasing, I believe.

In other words, -3, -2, -1, 2, 1, 1 can be a sequence, in my opinion. _________________

Keep on asking, and it will be given you;
keep on seeking, and you will find;
keep on knocking, and it will be opened to you.