It is currently 30 Oct 2020, 04:45
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.

In a certain sequence of numbers, each term after the first.

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
Joined: 02 Dec 2015
Posts: 7
Followers: 0

Kudos [?]: 0 [0], given: 3

In a certain sequence of numbers, each term after the first. [#permalink] New post 02 Jan 2016, 00:38
00:00

Question Stats:

6% (00:33) correct 93% (00:45) wrong based on 44 sessions
In a certain sequence of numbers, each term after the first term is found by multiplying the preceding term by 2 and then subtracting 3 from the product. If the 4th term in the sequence is 19, which of the following numbers are in the sequence? Indicate all such numbers.

A.5
B.8
C.11
D.16
E.22
F.35

Answer:
[Reveal] Spoiler:
a,c,f
[Reveal] Spoiler: OA
1 KUDOS received
Retired Moderator
User avatar
Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 173

Kudos [?]: 2977 [1] , given: 394

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 02 Jan 2016, 18:16
1
This post received
KUDOS
Expert's post
maverickjin8 wrote:
In a certain sequence of numbers, each term after the first term is found by multiplying the preceding term by 2 and then subtracting 3 from the product. If the 4th term in the sequence is 19, which of the following numbers are in the sequence? Indicate all such numbers.

A.5
B.8
C.11
D.16
E.22
F.35

The answer is a,c,f

I don't know how to solve this in a proper way.



Let the first term be \(x\). then the series is....

\(X\), \(2X -3\), \(4X - 9\), \(8X - 21\)

8X -21 =19
8X =40
X =5

So putting X =5 the series is 5, 7, 11, 19, 35, 67...............

So 5, 11 and 35..


PS: this question is very strangely worded! Can you share the source?
_________________

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: 10 Jun 2018
Posts: 32
Followers: 0

Kudos [?]: 21 [0], given: 4

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 03 Sep 2018, 15:50
The 4th term is 19.
5th term is (19*2)-3 = 35

the 3rd term is (19+3)/2 = 11

similarly 2nd and 1st term is respectively 7 and 5.

so answer is a,c,f
Intern
Intern
Joined: 17 Dec 2018
Posts: 3
Followers: 0

Kudos [?]: 2 [0], given: 2

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 14 Feb 2019, 02:07
sandy wrote:
PS: this question is very strangely worded! Can you share the source?


ETS Official Quantitative Reasoning Practice Questions, Chapter 7, Practice Set 1, Question 19
2 KUDOS received
Intern
Intern
Joined: 02 Aug 2019
Posts: 7
Followers: 0

Kudos [?]: 10 [2] , given: 0

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 02 Oct 2019, 08:59
2
This post received
KUDOS
I quickly came up with the formula: 2x - 3 = current term (where x = preceding term):

So 2x - 3 = 19
2x = 22
x = 11 --> C

2x - 3 = 11
2x = 14
x = 7

2x - 3 = 7
2x = 10
x =5 --> A

The next term in the sequence would be --> 2x - 3 = 2(19) - 3 = 35 --> F

Therefore, the answer is A, C, F
Intern
Intern
Joined: 18 Jul 2019
Posts: 32
Followers: 0

Kudos [?]: 4 [0], given: 2

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 02 Oct 2019, 11:32
c
1 KUDOS received
Intern
Intern
Joined: 19 Oct 2019
Posts: 4
Followers: 0

Kudos [?]: 3 [1] , given: 144

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 03 Nov 2019, 02:50
1
This post received
KUDOS
We can easily deduce here the general term of the sequence
\(a_{n+1}\) = \(2 * {a_n}\) - 3

We rewrite the formula for the forth and third term:
\(a_4\) = \(2 * {a_3}\) - 3

We resolve the equation for \(a_3\).
\(a_3\) = \(\frac{(a_4 +3)}{2} = \frac{22}{2}=11\)

Similarly, we calculate the preceding terms:
\(a_3\) = \(2 * {a_2} - 3\)
\(a_2\) = \(\frac{(a_3 +3)}{2} =\frac{14}{2}=7\)(not in the answer choices)

\(a_2\) = \(2 * {a_1}- 3\)
\(a_1\) = \(\frac{({a_2} +3)}{2} = \frac{10}{2}=5\) (in the answer choices)

From here we notice that the terms are smaller and smaller.
The smallest term in the answer choices is 5, so we have to look at higher terms (higher than the one given, which is the \(a_4\))

\(a_5\) =\(2 * {a_4} - 3\)
\(a_5\) =\(2*19 -3 = 35\)

Since we know that the fourth term is 19 and the fifth term is 35 there is no term in between, hence all the answers are:11, 5 and 35

Last edited by ElizabethCM on 03 Nov 2019, 04:24, edited 10 times in total.
1 KUDOS received
VP
VP
Joined: 20 Apr 2016
Posts: 1302
WE: Engineering (Energy and Utilities)
Followers: 22

Kudos [?]: 1332 [1] , given: 251

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 03 Nov 2019, 03:30
1
This post received
KUDOS
ElizabethCM wrote:
Below one solution using the sequence formula. I am sorry but I did not know how to edit the expressions here


Hi,
Plz be informed, you have to write it down. Attaching screenshot (for an answer) is not entertained.

I appreciate if you can read the RULES OF POSTING

RULES TO POST

The above link will guide. Any doubt give a shout
_________________

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


Rules for Posting

Got 20 Kudos? You can get Free GRE Prep Club Tests

GRE Prep Club Members of the Month:TOP 10 members of the month with highest kudos receive access to 3 months GRE Prep Club tests

1 KUDOS received
Intern
Intern
Joined: 19 Oct 2019
Posts: 4
Followers: 0

Kudos [?]: 3 [1] , given: 144

Re: In a certain sequence of numbers, each term after the first. [#permalink] New post 03 Nov 2019, 04:25
1
This post received
KUDOS
Thanks, Pranab, done, I just kept previewing but when we preview we do not see the final result formatted- sorry for so many edits !!!
Re: In a certain sequence of numbers, each term after the first.   [#permalink] 03 Nov 2019, 04:25
Display posts from previous: Sort by

In a certain sequence of numbers, each term after the first.

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

GRE Prep Club Forum Home| About| Terms and Conditions and Privacy Policy| 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®.