It is currently 14 Dec 2017, 20:23
My Tests

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.

term after the first term is equal to the preceding term

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
CEO
CEO
User avatar
Joined: 07 Jun 2014
Posts: 2910
GRE 1: 323 Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 49

Kudos [?]: 836 [1] , given: 146

term after the first term is equal to the preceding term [#permalink] New post 18 Jan 2016, 02:25
1
This post received
KUDOS
Expert's post
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
a1, a2, a3 ................ an

In the sequence above, each term after the first term is equal to the preceding term plus the constant c. If a1+a3+a5=27, what is the value of a2+a4 ?


a2+a4=


Practice Questions
Question: 24
Page: 336
Difficulty: easy

_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

2 KUDOS received
CEO
CEO
User avatar
Joined: 07 Jun 2014
Posts: 2910
GRE 1: 323 Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 49

Kudos [?]: 836 [2] , given: 146

Re: term after the first term is equal to the preceding term [#permalink] New post 18 Jan 2016, 04:52
2
This post received
KUDOS
Expert's post
Solution

This is clearly an arithmetic progression and we just need the first 5 terms. We can rewrite the progression as a - 2c, a - c, a , a + c, a + 2c. Here the difference between the terms is c as described in the problem

a1 + a3 + a5 = a - 2c + a + a+ 2c = 3a = 27. Hence a =9.

To find a2 + a4 = a - c + a + C = 2a =18.

The purpose of writing this series in the above form is to eliminate c as a variable. Hence answer is 18.
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Intern
Intern
Joined: 28 Mar 2016
Posts: 11
Followers: 0

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

Re: term after the first term is equal to the preceding term [#permalink] New post 30 Mar 2016, 09:05
i don't understand where you derive a - 2c and a + 2c from
1 KUDOS received
Director
Director
User avatar
Joined: 16 May 2014
Posts: 597
GRE 1: 326 Q165 V161
Followers: 72

Kudos [?]: 313 [1] , given: 64

Re: term after the first term is equal to the preceding term [#permalink] New post 01 Apr 2016, 02:30
1
This post received
KUDOS
Expert's post
Lets take a real arithmetic progression:

1, 5, 9 , 13, 17

As you can see any term of the above arithmetic progression is 4 greater than the previous term. 1+4 = 5... 5+4 = 9.... so on

So if we draw parallels with the question above here c = 4. Then we can write the above series taking the middle term 9 into account:
9-2*4, 9-4, 9 , 9+4, 9+2*4
a-2*c, a-c , a , a+c, a+2*c

Thats how Sandy derives the a+2c and a-2c terms
_________________

My GRE Resources
Free GRE resources | GRE Prep Club Quant Tests
If you find this post helpful, please press the kudos button to let me know ! :)

1 KUDOS received
Intern
Intern
Joined: 26 May 2017
Posts: 5
Followers: 0

Kudos [?]: 3 [1] , given: 6

Re: term after the first term is equal to the preceding term [#permalink] New post 29 Jun 2017, 20:10
1
This post received
KUDOS
If that is confusing then, you can say a, a+c, a+2c, a+3c, a+4c

a1+a3+a5 = 27

a + a+2c + a+4c = 27
a = 9-2c

now a2 + a4

a+c + a+3c
2a+4c
2(9-2c) + 4c
18-4c+4c

18/// is the answer.
Re: term after the first term is equal to the preceding term   [#permalink] 29 Jun 2017, 20:10
Display posts from previous: Sort by

term after the first term is equal to the preceding term

  Question banks Downloads My Bookmarks Reviews Important topics  


GRE Prep Club Forum Home| About| Terms of Use| GRE Prep Club Rules| Contact

Powered by phpBB © phpBB Group

Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.