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

 It is currently 18 Feb 2020, 23:57

### 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

# In a sequence of positive integers, every odd-numbered term after the

Author Message
TAGS:

### Hide Tags

Director
Joined: 18 Feb 2019
Posts: 659
Location: India
GMAT 1: 460 Q42 V13
GPA: 3.6
In a sequence of positive integers, every odd-numbered term after the  [#permalink]

### Show Tags

07 Mar 2019, 23:06
2
00:00

Difficulty:

45% (medium)

Question Stats:

69% (02:40) correct 31% (02:40) wrong based on 45 sessions

### HideShow timer Statistics

In a sequence of positive integers, every odd-numbered term after the first term is 1 more than twice the previous term and every even-numbered term starting from the 2nd term, is 2 less than 3 times the previous term. If the 2nd term of the sequence is 1, then how many terms out of the first 20 terms are even?

A. 0
B. 5
C. 10
D. 15
E. 20
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3239
Re: In a sequence of positive integers, every odd-numbered term after the  [#permalink]

### Show Tags

08 Mar 2019, 01:00
1

Solution

Given:
• In a sequence of positive integers, every odd-numbered term after the first term is 1 more than twice the previous term and every even-numbered term starting from the 2nd term, is 2 less than 3 times the previous term.
• The 2nd term of the sequence is 1.

To find:
• Number of even terms in the first 20 terms of the series.

Approach and Working:
The 2nd term is 1 and it is 2 less than 3 times the 1st term
• Therefore, the 1st term = (1 + 2)/3 = 1
So, both 1st and 2nd terms are odd numbers.

For odd numbered terms,
• Value = 2 x previous term + 1 = even + odd = odd

For even numbered terms,
• Value = 3 x previous term – 2 = 3 x odd – 2 = odd – even = odd

Therefore, all the terms in the series is odd.

Hence, the correct answer is option A.

_________________
Manager
Joined: 18 Jan 2018
Posts: 50
Re: In a sequence of positive integers, every odd-numbered term after the  [#permalink]

### Show Tags

08 Mar 2019, 03:59
Look for odd & even numbers in the sequence. All numbers turn out to be odd. Hence even numbers are 0.
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 5931
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: In a sequence of positive integers, every odd-numbered term after the  [#permalink]

### Show Tags

10 Mar 2019, 08:56
kiran120680 wrote:
In a sequence of positive integers, every odd-numbered term after the first term is 1 more than twice the previous term and every even-numbered term starting from the 2nd term, is 2 less than 3 times the previous term. If the 2nd term of the sequence is 1, then how many terms out of the first 20 terms are even?

A. 0
B. 5
C. 10
D. 15
E. 20

first term =
1 more than twice the previous term = 1 + 2* previous term
even term + odd (1) = odd term always
2nd term
2 less than 3 times the previous term
previous term odd ie odd 3*odd -2 = odd-2 = odd term
so even terms = 0
IMO A
Re: In a sequence of positive integers, every odd-numbered term after the   [#permalink] 10 Mar 2019, 08:56
Display posts from previous: Sort by