Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 28 May 2015, 14:28

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Weird Integer Problem

Author Message
TAGS:
Manager
Joined: 27 Oct 2009
Posts: 151
Location: Montreal
Schools: Harvard, Yale, HEC
Followers: 1

Kudos [?]: 28 [0], given: 18

Weird Integer Problem [#permalink]  14 Nov 2009, 19:05
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
Attachments

Arithmetic2.jpg [ 65.1 KiB | Viewed 741 times ]

SVP
Joined: 30 Apr 2008
Posts: 1891
Location: Oklahoma City
Schools: Hard Knocks
Followers: 34

Kudos [?]: 470 [1] , given: 32

Re: Weird Integer Problem [#permalink]  14 Nov 2009, 19:30
1
KUDOS
We know that 450 * y will equal a perfect cube, and we're told that n and y are postiive, so we do not have to worry about that.

450 * y = some cube. Break down 450 into primes

3 * 3 * 5 * 5 * 2

So 3 * 3 * 5 * 5 * 2 must equal some cube. We know that if we had three 3's, three 5's and three 2's, then that would be a perfect cube.

so if you let y equal what we are missing to give us three of each, then y must break down into the primes of 3 * 5 * 2 * 2. This is I. If we know that Y breaks doen to 2 * 5 * 2^2, and that is the denominator with y as the numerator, this will equal 1. for the same reason, we know that II and III will not result in integers.

ezinis wrote:
If n and y are positive integers and $$450y = n^3$$, which of the following must be an integer?

I. $$\frac{y}{3 x 2^2 x 5}$$

II. $$\frac{y}{3^2 x 2 x 5}$$

III. $$\frac{y}{3 x 2 x 5^2}$$

a) None

b) I only

c) II only

d) III only

e I, II and III

_________________

------------------------------------
J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a.

GMAT Club Premium Membership - big benefits and savings

VP
Joined: 05 Mar 2008
Posts: 1473
Followers: 11

Kudos [?]: 219 [1] , given: 31

Re: Weird Integer Problem [#permalink]  14 Nov 2009, 19:31
1
KUDOS
ezinis wrote:

450 y = n^3

450 = 3*3*5*5*2

in order for 450 to have a cube root we need 3 of each number of 3*3*3*5*5*5*2*2*2

we already have two 3's and two 5's and one 2

therefore we need one 3, one 5, and 2 twos

or 3 x 5 x 2^2

Manager
Joined: 27 Oct 2009
Posts: 151
Location: Montreal
Schools: Harvard, Yale, HEC
Followers: 1

Kudos [?]: 28 [0], given: 18

Re: Weird Integer Problem [#permalink]  15 Nov 2009, 05:36
Thanks jallenmorris +1 from me
Re: Weird Integer Problem   [#permalink] 15 Nov 2009, 05:36
Similar topics Replies Last post
Similar
Topics:
1 Word Translation problem: bonus is given in a weird way 4 14 Jul 2013, 13:08
integer problem 0 18 May 2011, 02:48
32 Mauritius was a British colony for almost 200 years, 20 05 Dec 2008, 19:32
1 integer problem 1 04 Jun 2009, 20:35
I have a weird problem... I'm aiming for 50, 51 in math. I 3 21 Mar 2007, 00:54
Display posts from previous: Sort by