GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 25 Jan 2020, 20:22 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # In a certain sequence a1, a2, ...an..., for n>1, each term is the sum

Author Message
TAGS:

### Hide Tags

Manager  G
Joined: 30 May 2018
Posts: 88
GMAT 1: 620 Q42 V34
WE: Corporate Finance (Commercial Banking)
In a certain sequence a1, a2, ...an..., for n>1, each term is the sum  [#permalink]

### Show Tags

9 00:00

Difficulty:   65% (hard)

Question Stats: 52% (01:58) correct 48% (01:55) wrong based on 63 sessions

### HideShow timer Statistics

In a certain sequence a1, a2, ...an..., for n>1, each term is the sum of all previous terms. If an=S, in terms of S, a(n+3)=?

(A) 3S
(B) 4S
(C) 6S
(D) 8S
(E) 9S
Manager  G
Joined: 21 Feb 2019
Posts: 124
Location: Italy
Re: In a certain sequence a1, a2, ...an..., for n>1, each term is the sum  [#permalink]

### Show Tags

2
$$a_n = S$$
$$a_{n+1} = S + S = 2S$$
$$a_{n+2} = 2S + 2S = 4S$$
$$a_{n+3} = 4S + 4S = 8S$$
Intern  B
Joined: 18 Jan 2019
Posts: 28
Re: In a certain sequence a1, a2, ...an..., for n>1, each term is the sum  [#permalink]

### Show Tags

lucajava wrote:
$$a_n = S$$
$$a_{n+1} = S + S = 2S$$
$$a_{n+2} = 2S + 2S = 4S$$
$$a_{n+3} = 4S + 4S = 8S$$

can you explain the logic behind this?
Manager  G
Joined: 21 Feb 2019
Posts: 124
Location: Italy
Re: In a certain sequence a1, a2, ...an..., for n>1, each term is the sum  [#permalink]

### Show Tags

1
Ish1996 each term is the sum of all previous terms, so if $$a_n = S$$, $$a_{n+1}$$ is equal to all previous terms of $$a_n$$, which give S as result, in addition to $$a_n$$ itself, which is S.
Repeat this reasoning for the following ones and you will get the correct answer.

Posted from my mobile device Re: In a certain sequence a1, a2, ...an..., for n>1, each term is the sum   [#permalink] 22 Apr 2019, 01:45
Display posts from previous: Sort by

# In a certain sequence a1, a2, ...an..., for n>1, each term is the sum  