mgmat qn

Expert replies

mirantdon: Master | Next Rank: 500 Posts; Posts: 135; Joined: Thu May 05, 2011 9:00 amFollowed by: 1 member; Thanked: 4 times; GMAT Score:700

by mirantdon » Mon May 30, 2011 9:01 am

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
a. x = w
b. x > w
c. x/y is an integer
d. w/z is an integer
e. x/z is an integer

oa after some discussions

Like this post

Source: Beat The GMAT — Problem Solving | Mon May 30, 2011 9:01 am

sivaelectric: Master | Next Rank: 500 Posts; Posts: 439; Joined: Sat Aug 09, 2008 8:32 amFollowed by: 28 members; Location: India; Thanked: 34 times

by sivaelectric » Mon May 30, 2011 9:08 am

IMO A

If I am wrong correct me

, If my post helped let me know by clicking the Thanks button

.

Chitra Sivasankar Arunagiri

Like this post

m.abdulk: Junior | Next Rank: 30 Posts; Posts: 13; Joined: Thu Feb 17, 2011 2:37 am

by m.abdulk » Mon May 30, 2011 9:23 am

can someone explain me how can y and z be related as they are a set of numbers??? or shuld it have been x and w???

if its w and x then

1 2 3 4 5 6 7 =27

1 2 3 4 5 6 7 8 9 10 =>54

This can be one such set.

Someone pls help

Like this post

SoCan: Senior | Next Rank: 100 Posts; Posts: 97; Joined: Sun May 15, 2011 9:19 amFollowed by: 1 member; Thanked: 18 times

by SoCan » Mon May 30, 2011 9:27 am

Because y=2z and z is an integer, we know that y is even. Whenever you see 'even number of consecutive integers' on the GMAT, one of the first things you should think about is that the average of this set cannot be an integer. This is true because the average of a set of consecutive integers is the same as the median. When the set has an odd number of elements, the median is the middle integer. When a set has an even number of elements, the median is the average of the two middle integers. Since these two integers are consecutive, the average will be a decimal.

Since this question asks which of the following CANNOT be true, look for the expression of the average of the set. That's C (sum of the set divided by the number of elements in the set).

Like this post

SoCan: Senior | Next Rank: 100 Posts; Posts: 97; Joined: Sun May 15, 2011 9:19 amFollowed by: 1 member; Thanked: 18 times

by SoCan » Mon May 30, 2011 9:33 am

sivaelectric wrote:IMO A

Be careful. Perhaps you thought that x and y start with the same integer, but it's possible in many scenarios to have x=w.

Last edited by SoCan on Mon May 30, 2011 10:42 am, edited 1 time in total.

Like this post

tomada: Master | Next Rank: 500 Posts; Posts: 406; Joined: Mon Jan 25, 2010 11:36 amFollowed by: 4 members; Location: Syracuse, NY; Thanked: 23 times; GMAT Score:740

by tomada » Mon May 30, 2011 10:37 am

I am baffled as to how someone could choose (A). All we need to do to rule out answer 'A' is find a single scenario in which X=W.

Say Z=1 and Y=2. This satisfies the conditions that Y=2Z AND that Y,Z are positive integers.

Say W=11. Can X=11 as the sum of 2 consecutive integers? Yes, if the integers are 5 and 6.

Thus, X can equal W, and choice (A) cannot be correct.

I'm really old, but I'll never be too old to become more educated.

Like this post

cans: Legendary Member; Posts: 1309; Joined: Mon Apr 04, 2011 5:34 amFollowed by: 123 members; Location: India; Thanked: 310 times; GMAT Score:750

by cans » Mon May 30, 2011 10:53 am

Lets say z=1, and thus w is sum of 1 consecutive integer and thus w is any +ve integer.
also then y=2, and thus x is sum of 2 consecutive integers which is always odd (odd+even=odd)
thus x/y which is (odd no.)/2 in this case is not an integer.
Thus C

Like this post

[email protected]: Legendary Member; Posts: 934; Joined: Tue Nov 09, 2010 5:16 amFollowed by: 14 members; Location: AAMCHI MUMBAI LOCAL; Thanked: 63 times

by [email protected] » Mon Jun 13, 2011 3:24 am

IT IS TIME TO BEAT THE GMAT

LEARNING, APPLICATION AND TIMING IS THE FACT OF GMAT AND LIFE AS WELL... KEEP PLAYING!!!

Whenever you feel that my post really helped you to learn something new, please press on the 'THANK' button.

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review