Last visit was: 22 Apr 2026, 07:02 It is currently 22 Apr 2026, 07:02
Close
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
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
tejal777
Joined: 25 Oct 2008
Last visit: 09 Jan 2012
Posts: 360
Own Kudos:
Given Kudos: 100
Location: Kolkata,India
Posts: 360
Kudos: 6,991
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
asterixmatrix
Joined: 12 Oct 2009
Last visit: 29 Jan 2010
Posts: 64
Own Kudos:
Given Kudos: 3
Posts: 64
Kudos: 163
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
lagomez
Joined: 05 Mar 2008
Last visit: 18 Sep 2011
Posts: 1,224
Own Kudos:
563
 [1]
Given Kudos: 31
Posts: 1,224
Kudos: 563
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
study
Joined: 05 Oct 2008
Last visit: 22 Mar 2022
Posts: 159
Own Kudos:
Given Kudos: 22
Posts: 159
Kudos: 4,016
Kudos
Add Kudos
Bookmarks
Bookmark this Post
What is GP and what is the formula about?

Bunuel, can you please explain this one.

Thank you.
User avatar
h2polo
Joined: 13 Aug 2009
Last visit: 08 Mar 2012
Posts: 101
Own Kudos:
378
 [1]
Given Kudos: 16
Posts: 101
Kudos: 378
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
GP is short for Geometric Progression. You can check out the wikipedia article for a detailed explaination:

https://en.wikipedia.org/wiki/Geometric_progression

But don't get caught up on trying to remember formulas. The key is to understand what you are looking at.

Just like lagomez said, it is about pattern recognition:

Here is the pattern I used:

2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8
Factor out the two:
2*(1+1+2+2^2+2^3+2^4+2^5+2^6+2^7)=2*(2+2^1+2^2+2^3+2^4+2^5+2^6+2^7)
Keep factoring out the two...
2*2*(2+2+2^2+2^3+2^4+2^5+2^6)
2*2*2*(2+2+2^2+2^3+2^4+2^5)
2*2*2*2*(2+2+2^2+2^3+2^4)
2*2*2*2*2*(2+2+2^2+2^3)
2*2*2*2*2*2*(2+2+2^2)
2*2*2*2*2*2*2*(2+2)
2*2*2*2*2*2*2*2*(2)
OR
2^9=512
User avatar
ctrlaltdel
Joined: 24 Jul 2009
Last visit: 11 Jan 2023
Posts: 59
Own Kudos:
602
 [2]
Given Kudos: 124
Location: United States
GMAT 1: 590 Q48 V24
GMAT 1: 590 Q48 V24
Posts: 59
Kudos: 602
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
study,

Here u go....hope it is useful.

Cheers

Kudos, if u feel it was helpful.
Attachments

arith_and_geom_progressions.pdf [182.25 KiB]
Downloaded 493 times

User avatar
ctrlaltdel
Joined: 24 Jul 2009
Last visit: 11 Jan 2023
Posts: 59
Own Kudos:
602
 [2]
Given Kudos: 124
Location: United States
GMAT 1: 590 Q48 V24
GMAT 1: 590 Q48 V24
Posts: 59
Kudos: 602
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
One more...Source:tcy

Kudos if u find it helpful.
Attachments

sequence.pdf [99.51 KiB]
Downloaded 201 times

User avatar
study
Joined: 05 Oct 2008
Last visit: 22 Mar 2022
Posts: 159
Own Kudos:
Given Kudos: 22
Posts: 159
Kudos: 4,016
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I tried to apply the GP formula but something is wrong - Can someone help please. Thanks.


a = the first term
r = the common ratio,
Tn = nth term and
Sn = sum of n terms

Sum of first n terms of G.P:
Sn = [a (r^n - 1)] / a(r - 1)
where r > 1


Sum
[a (r^n - 1)] = 2 (2^10 - 1) = 2 * (1024 -1) = 2*1023
a(r - 1) = 2 ( 2 - 1) = 2

Hence sum = 2 * 1023 / 2 = 1023 that is incorrect
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 22 Apr 2026
Posts: 109,743
Own Kudos:
Given Kudos: 105,819
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,743
Kudos: 810,576
Kudos
Add Kudos
Bookmarks
Bookmark this Post
study
I tried to apply the GP formula but something is wrong - Can someone help please. Thanks.


a = the first term
r = the common ratio,
Tn = nth term and
Sn = sum of n terms

Sum of first n terms of G.P:
Sn = [a (r^n - 1)] / a(r - 1)
where r > 1


Sum
[a (r^n - 1)] = 2 (2^10 - 1) = 2 * (1024 -1) = 2*1023
a(r - 1) = 2 ( 2 - 1) = 2

Hence sum = 2 * 1023 / 2 = 1023 that is incorrect

Sum of the terms of geometric progression is given by: \(Sum=\frac{a*(r^{n}-1)}{r-1}\), where \(a\) is the first term, \(n\) # of terms and \(r\) is a common ratio \(>1\).

In our original question we have 2 plus G.P. with 8 terms, so:

\(2+(2+2^2+2^3+2^4+2^5+2^6+2^7+2^8)=2+\frac{2*(2^{8}-1)}{2-1}=1024\)



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
Moderator:
Math Expert
109743 posts