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

Redeem

Help me solv this?

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 101
Joined: Sun Jun 03, 2012 10:10 pm
Thanked: 10 times
Followed by:1 members

by everything's eventual » Thu Sep 06, 2012 7:30 pm
I feel that some info is missing here.

Lets take (ii) and (iii) into consideration first.

(ii) will be even if y is odd and odd is y is even.

(iii) will be even if x is even and odd is x is odd.

Now considering(i)

y ^ (x-1)

Consider x as odd ( say 3) and y as even ( say 2). So after substituting in the equation we get value as 4 viz even. Now consider, x as even ( say 2) and y as odd ( say 3). Now we get value as 3 viz odd.

According to my solution none of them "must" be even.
Top
Master | Next Rank: 500 Posts
Posts: 101
Joined: Sun Jun 03, 2012 10:10 pm
Thanked: 10 times
Followed by:1 members

by everything's eventual » Thu Sep 06, 2012 7:32 pm
I think that the problem states that both x and y are even positive integers. In this case the answer is (d) : (i) and (iii) only
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 134
Joined: Fri Apr 06, 2012 3:11 am
Thanked: 35 times
Followed by:5 members

by Shalabh's Quants » Fri Sep 07, 2012 7:15 am
everything's eventual wrote:I think that the problem states that both x and y are even positive integers. In this case the answer is (d) : (i) and (iii) only
(iii) is not necessarily an even. Take x=6, then x/2 would be Odd.
Shalabh Jain,
e-GMAT Instructor
Top

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 » Fri Sep 07, 2012 8:46 am
disturbedmimi wrote:If both x and y are positive integers then which of the following expressions must also be even?
i.. y^x-1
ii.y-1
iii. x/2

(a) i only
(b) ii only
(c) iii. only
(d) i and iii only
(e) i, ii, and iii
This question could use some clarification before we try to answer it.

First, there's some uncertainty with ". . . which of the following expressions must also be even?"
Also?
Is one or both of the given variables (x, y) supposed to be even?

Second, there's some possible ambiguity with the first expresson: y^x-1
Does this mean (y^x) - 1 or y^(x-1)?
Some brackets (or even some spaces) would help prevent any ambiguity.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Master | Next Rank: 500 Posts
Posts: 101
Joined: Sun Jun 03, 2012 10:10 pm
Thanked: 10 times
Followed by:1 members

by everything's eventual » Fri Sep 07, 2012 9:14 am
@ Shalabh...yes very silly of me...in that case we have only (i)
Top
Post new topic Post Reply
• Page 1 of 1