OG 111- Question No. 132

This topic has expert replies
Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 am
Thanked: 5 times
Followed by:2 members

OG 111- Question No. 132

by Cybermusings » Fri May 25, 2007 11:44 pm
I didn't particularly catch the explanation given in the OG....Please help!

If the integer n is greater than 1, is n equal to 2?

1) n has exactly 2 positive factors

2) The difference of any 2 distinct positive factors of n is odd


OA here is B....However, consider an example where n=4....Factors = 4,2,1 ......Now 4-1 =3 (Odd)....So how is B sufficient....I think I am not understanding the Statement too well!

User avatar
Master | Next Rank: 500 Posts
Posts: 400
Joined: Sat Mar 10, 2007 4:04 am
Thanked: 1 times
Followed by:1 members

by f2001290 » Sat May 26, 2007 4:48 am
1,2 and 4 are the factors of 4. In this case 4-2 is even.

Question says that difference of "any" two positive factors is odd.

So B alone is suuficient

Junior | Next Rank: 30 Posts
Posts: 21
Joined: Wed Jan 24, 2007 4:28 pm
Location: NJ

DS #132 (OG 11th)

by Kansonne » Mon Oct 01, 2007 12:21 pm
[quote="f2001290"]1,2 and 4 are the factors of 4. In this case 4-2 is even.

Question says that difference of "any" two positive factors is odd.

So B alone is suuficient[/quote]

Hi, f2001290---

Can you pls explain a little more RE: "any"?

I thought that 4 would be a val for n that satisfied statement (2). I saw from the MGMAT forum that we are supposed to take it that "any" means "all", but I interpreted "any distinct positive factors" to mean all "eligible" factors of n.

4's factors:
1 and 4,
2 and 2

I thought that 2 and 2 should be tossed out since they are not distinct factors of 4, leaving only 4 and 1 to be considered.

Can you please help me understand where I'm going wrong?

Thanks!

Master | Next Rank: 500 Posts
Posts: 321
Joined: Tue Aug 28, 2007 5:42 am
Thanked: 1 times

by kajcha » Tue Oct 02, 2007 9:28 am
kansonne, when you have to take factors of a number you consider all factors together. In this example 4 has 1,2 and 4 as factors.

Stmt 2 says that diff of any 2 factors is odd... for this case diff of 4 and 1 is 3. However, diff of 4 and 2 is even. So 4 does not satisfy stmt 2.