x is the sum of y consecutive integers. w is the sum of z consecutive integers. If y = 2z, and y and z are both positive integers, then each of the following could be true EXCEPT:
1. x = w
2. x > w
3. x/y is an integer
4. w/z is an integer
5. x/z is an integer
Answer is 3
x is the sum of y consecutive integers (manhattan gmat)
This topic has expert replies
-
- Newbie | Next Rank: 10 Posts
- Posts: 6
- Joined: Mon Sep 14, 2009 11:02 pm
-
- Master | Next Rank: 500 Posts
- Posts: 182
- Joined: Sun Aug 02, 2009 7:19 pm
- Thanked: 18 times
- GMAT Score:680
Answer is C.
You just need to remember the below property :
1)The sum of an even number of consecutive integers is never a multiple of the number of terms.
2)The sum of an odd number of consecutive integers is alwys a multiple of the number of terms
Lets take examples.
Property 1
Say the sum of 1,2,3,4
4(even) consecutive integers,sum : 10 , which is not a multiple of 4.
Will hold for any such set of numbers
Property 2
5(odd) consecutive integers : 1,2,3,4,5,sum =15 which is a multiple of 5.
Hence in the question we have,
x which is the sum of an even number of consecutive integers since y=2y(will be even since 2 is even).
Hence
X/Y cannot be an integer.
You just need to remember the below property :
1)The sum of an even number of consecutive integers is never a multiple of the number of terms.
2)The sum of an odd number of consecutive integers is alwys a multiple of the number of terms
Lets take examples.
Property 1
Say the sum of 1,2,3,4
4(even) consecutive integers,sum : 10 , which is not a multiple of 4.
Will hold for any such set of numbers
Property 2
5(odd) consecutive integers : 1,2,3,4,5,sum =15 which is a multiple of 5.
Hence in the question we have,
x which is the sum of an even number of consecutive integers since y=2y(will be even since 2 is even).
Hence
X/Y cannot be an integer.