Last visit was: 23 Apr 2026, 14:16 It is currently 23 Apr 2026, 14:16
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
505-555 (Easy)|   Sequences|      
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,785
Own Kudos:
810,852
 [11]
Given Kudos: 105,853
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,785
Kudos: 810,852
 [11]
In the sequence above, each term after the first term is equal to the 03 Dec 2018, 02:57
Kudos
Add Kudos
10
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

15% (low)

Question Stats:

85% (02:19) correct 15% (02:18) wrong based on 208 sessions

History

Date
Time
Result
Not Attempted Yet
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 \(a_1+a_3+a_5=27\), what is the value of \(a_2 + a_4\) ?

A. 5
B. 9
C. 13
D. 18
E. 22
ShowHide Answer
Official Answer
D
User avatar
Archit3110
User avatar
Major Poster
Joined: 18 Aug 2017
Last visit: 23 Apr 2026
Posts: 8,628
Own Kudos:
5,190
Given Kudos: 243
Status:You learn more from failure than from success.
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1: 545 Q79 V79 DI73
GMAT Focus 2: 645 Q83 V82 DI81
GPA: 4
WE:Marketing (Energy)
Products:
GMAT Club Tests Forum Quiz
GMAT Focus 2: 645 Q83 V82 DI81
Posts: 8,628
Kudos: 5,190
In the sequence above, each term after the first term is equal to the 03 Dec 2018, 03:40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
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 \(a_1+a_3+a_5=27\), what is the value of \(a_2 + a_4\) ?

A. 5
B. 9
C. 13
D. 18
E. 22
Show more

took me >2 mins to understand question ,if any one has any other solution please do provide solution:

I assumed a1=3
and c to be 3 as well
so
a1=3;a2=6;a3=9;a4=12;a5=15

a1+a3+a5=27 9 given

a1+a2+c+a4+c=27
a2+a4+2c+a1=27

since a1=c=3
so a2+a4= 27-(2*3+3)
a2+a4=27-9
a2+a4=18

IMO D....
User avatar
baru
User avatar
Joined: 18 Jan 2018
Last visit: 02 Dec 2020
Posts: 202
Own Kudos:
312
 [2]
Given Kudos: 72
Location: India
Concentration: General Management, Healthcare
Schools: ISB '21 Booth '22 IIMB
GPA: 3.87
WE:Design (Manufacturing)
Schools: ISB '21 Booth '22 IIMB
Posts: 202
Kudos: 312
 [2]
In the sequence above, each term after the first term is equal to the 04 Dec 2018, 07:14
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
given a1+a3+a5 = 27
I assumed constant C = 1 , then sequence ==> 1,2,3,4,5,6,7
==> 1+3+5 = 9 ==>if I make C =3 that will satisfy given condition
then sequence becomes ==> 3,6,9,12,15,18...

finally a2+a4 = 6+12 = 18==> Option D
User avatar
EncounterGMAT
User avatar
Joined: 10 Oct 2018
Last visit: 16 Oct 2019
Posts: 317
Own Kudos:
632
 [1]
Given Kudos: 185
Status:Whatever it takes!
GPA: 4
Posts: 317
Kudos: 632
 [1]
In the sequence above, each term after the first term is equal to the 04 Dec 2018, 09:01
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
let a2=a1+c, a3=a1+2
a1+a1+2c+a1+4c=27
3a1+6c=27
a1+c=9...............(eq. 1)

We need to find a2+a4
a2+a4=a1+c+a1+3c= 2a1+4c= 2(a1+2c)=2(9) .....from eq. 1=18

Therefore, answer is option D
User avatar
T1101
User avatar
Joined: 07 Aug 2018
Last visit: 18 Nov 2021
Posts: 79
Own Kudos:
358
 [1]
Given Kudos: 247
Location: United States (MA)
GMAT 1: 560 Q39 V28
GMAT 2: 670 Q48 V34
GMAT 2: 670 Q48 V34
Posts: 79
Kudos: 358
 [1]
In the sequence above, each term after the first term is equal to the 05 Dec 2018, 02:33
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
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 \(a_1+a_3+a_5=27\), what is the value of \(a_2 + a_4\) ?

A. 5
B. 9
C. 13
D. 18
E. 22
Show more

Took me quite some time to figure out how to get to an answer, since I was not able to calculate a definite value for \(a_1\)

\(a_1+a_3+a_5=27\) \(-->\) \(a_3=a_1+2c\) and \(a_5=a_1+4c\)

Rewrite the equation: \(a_1+a_1+2c+a_1+4c=27\) \(-->\) \(a_1+2c=9\) At this points I was quite stuck... But I then assumed integer values for \(c\)

\(c=0\) \(-->\) \(a_1=9\) \(-->\) \(a_2 + a_4=9+9=18\)
\(c=1\) \(-->\) \(a_1=7\) \(-->\) \(a_2 + a_4=8+10=18\)
\(c=2\) \(-->\) \(a_1=5\) \(-->\) \(a_2 + a_4=7+11=18\)
\(c=3\) \(-->\) \(a_1=3\) \(-->\) \(a_2 + a_4=6+12=18\)
\(c=4\) \(-->\) \(a_1=1\) \(-->\) \(a_2 + a_4=5+13=18\)

As we can see any value of \(a_1\) will result in \(a_2 + a_4=18\), hence D.

Bunuel is there any faster way to solve this question? I was quite stuck thinking i was doing something wrong, because I could not solve for a value of \(a_1\)
User avatar
jfranciscocuencag
User avatar
Joined: 12 Sep 2017
Last visit: 17 Aug 2024
Posts: 227
Own Kudos:
144
 [2]
Given Kudos: 132
Posts: 227
Kudos: 144
 [2]
In the sequence above, each term after the first term is equal to the 20 Jan 2019, 18:01
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
My answer:

Sum = (Avrg)(N)

27/3 = Avrg = 9

Since 9 = N3

N2 + N4 MUST be 18 since (N2 + N4)/2 = N3 = 9

D
avatar
thyagi51
avatar
Joined: 21 Jan 2019
Last visit: 08 Feb 2019
Posts: 6
Own Kudos:
2
 [1]
Given Kudos: 4
Posts: 6
Kudos: 2
 [1]
In the sequence above, each term after the first term is equal to the 22 Jan 2019, 05:27
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I started putting in answer options .. for example my reduced equation was 2a1+4c...
If 2a1+ 4c = 18
Then A1+2c= 9...
Therefore answer option d is correct

Posted from my mobile device
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,733
Own Kudos:
36,451
 [4]
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,733
Kudos: 36,451
 [4]
In the sequence above, each term after the first term is equal to the 15 Dec 2021, 08:56
4
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
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 \(a_1+a_3+a_5=27\), what is the value of \(a_2 + a_4\) ?

A. 5
B. 9
C. 13
D. 18
E. 22
Show more


By definition:
a1 = a1
a2 = a1 + c
a3 = a1 + c + c = a1 + 2c
a4 = a1 + c + c + c = a1 + 3c
a5 = a1 + c + c + c + c = a1 + 4c


GIVEN: a1+a3+a5=27
We can write: a1 + (a1 + 2c) + (a1 + 4c) = 27
Simplify: 3a1 + 6c = 27
Divide both sides by 3 to get: a1 + 2c = 9


What is the value of \(a2+a4\)
a2 + a4 = (a1 + c) + (a1 + 3c)
= 2a1 + 4c
= 2(a1 + 2c)
= 2(9)
= 18

Answer: D
User avatar
mpobisetty
User avatar
Joined: 06 Dec 2021
Last visit: 27 Oct 2025
Posts: 65
Own Kudos:
30
Given Kudos: 5
GMAT 1: 690 Q49 V36
GMAT 1: 690 Q49 V36
Posts: 65
Kudos: 30
In the sequence above, each term after the first term is equal to the 16 Dec 2021, 07:11
Kudos
Add Kudos
Bookmarks
Bookmark this Post
a + (a + 2d) + (a + 4d) = 27
So, 3a + 6d = 27
So, a + 2d = 9

We have to find out (a + d) + (a + 3d) = 2a + 4d = 2*(a + 2d) = 2*9 = 18
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,962
Own Kudos:
1,117
Posts: 38,962
Kudos: 1,117
In the sequence above, each term after the first term is equal to the 02 Oct 2024, 09:19
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109785 posts
Krunaal
Tuck School Moderator
853 posts