BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Alpha Sequence

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 168
Joined: Thu Nov 01, 2012 7:43 pm
Thanked: 1 times

Alpha Sequence

by pareekbharat86 » Thu Nov 14, 2013 4:30 pm
An infinite sequence of positive integers is called an "alpha sequence" if the number of even integers in the sequence is finite. If S is an infinite sequence of positive integers, is S an alpha sequence?
(1) The first ten integers in S are even.
(2) An infinite number of integers in S are odd.

OA is E.
Thanks,
Bharat.
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Thu Nov 14, 2013 5:00 pm
pareekbharat86 wrote:An infinite sequence of positive integers is called an "alpha sequence" if the number of even integers in the sequence is finite. If S is an infinite sequence of positive integers, is S an alpha sequence?

(1) The first ten integers in S are even.
(2) An infinite number of integers in S are odd.
Target question: Is S an alpha sequence?

Let's jump straight too . . .

Statements 1 and 2 combined
There are several possible sets that satisfy both conditions. Here are two:
Case a: S = {2,4,6,8,10,12,14,16,18,20,21,23,25,27,29,31...all odd integers...etc}, in which case S is an alpha sequence
Case b: S = {2,4,6,8,10,12,14,16,18,20,21,22,23,24,25,26,27,28,29,30...}, in which case S is NOT an alpha sequence
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer = E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 490
Joined: Thu Jul 04, 2013 7:30 am
Location: Chennai, India
Thanked: 83 times
Followed by:5 members

by Uva@90 » Thu Nov 14, 2013 8:28 pm
pareekbharat86 wrote:An infinite sequence of positive integers is called an "alpha sequence" if the number of even integers in the sequence is finite. If S is an infinite sequence of positive integers, is S an alpha sequence?
(1) The first ten integers in S are even.
(2) An infinite number of integers in S are odd.

OA is E.
Hi Pareekbharat86,
To Find: Does Sequence S has finite number of Even Integers. (YES/NO Type)

Statement1 : It talk about only first ten. Rest of the sequence is unsaid.
So Insufficient.

Statement2 : It talks about Odd.
Hence Insufficient.

1+2
Nothing about Finite sequence of Even Integers is said.
Hence Insufficient.

Answer is E

Regards,
Uva.
Known is a drop Unknown is an Ocean
Top
Master | Next Rank: 500 Posts
Posts: 447
Joined: Fri Nov 08, 2013 7:25 am
Thanked: 25 times
Followed by:1 members

by Mathsbuddy » Fri Nov 22, 2013 9:49 am
An infinite sequence of positive integers is called an "alpha sequence" if the number of even integers in the sequence is finite. If S is an infinite sequence of positive integers, is S an alpha sequence?
(1) The first ten integers in S are even: this doesn't say that these are the only even numbers, therefore INSUFFICIENT
(2) An infinite number of integers in S are odd: this doesn't say if there are any even numbers INSUFFICIENT

Combined: No certainty that the even numbers are finite: INSUFFICIENT
Top
Post new topic Post Reply
• Page 1 of 1