The useful life of a certain piece of equipment is determine : GMAT Problem Solving (PS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 18 Jan 2017, 21:45

### 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

# The useful life of a certain piece of equipment is determine

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

CEO
Joined: 21 Jan 2007
Posts: 2756
Location: New York City
Followers: 11

Kudos [?]: 851 [0], given: 4

The useful life of a certain piece of equipment is determine [#permalink]

### Show Tags

20 Feb 2008, 14:00
00:00

Difficulty:

(N/A)

Question Stats:

84% (01:59) correct 16% (00:38) wrong based on 73 sessions

### HideShow timer Statistics

The useful life of a certain piece of equipment is determined by the following formula: u =(8d)/h^2, where u is the useful life of the equipment, in years, d is the density of the underlying material, in g/cm3, and h is the number of hours of daily usage of the equipment. If the density of the underlying material is doubled and the daily usage of the equipment is halved, what will be the percentage increase in the useful life of the equipment?

A. 300%
B. 400%
C. 600%
D. 700%
E. 800%

OPEN DISCUSSION OF THIS QUESTION IS HERE: the-useful-life-of-a-certain-piece-of-equipment-is-determine-101496.html
_________________

You tried your best and you failed miserably. The lesson is 'never try'. -Homer Simpson

Last edited by Bunuel on 27 Oct 2013, 04:21, edited 1 time in total.
Renamed the topic, edited the question, added the OA and moved to PS forum.
Director
Joined: 01 Jan 2008
Posts: 629
Followers: 4

Kudos [?]: 175 [0], given: 1

Re: MGMAT - Formula [#permalink]

### Show Tags

20 Feb 2008, 14:09
bmwhype2 wrote:
The useful life of a certain piece of equipment is determined by the following formula: u =(8d)/h2, where u is the useful life of the equipment, in years, d is the density of the underlying material, in g/cm3, and h is the number of hours of daily usage of the equipment. If the density of the underlying material is doubled and the daily usage of the equipment is halved, what will be the percentage increase in the useful life of the equipment?

300%
400%
600%
700%
800%

if it's h^2 then D is the answer
I really don't like units though
Senior Manager
Joined: 20 Dec 2004
Posts: 255
Followers: 6

Kudos [?]: 106 [1] , given: 0

Re: MGMAT - Formula [#permalink]

### Show Tags

20 Feb 2008, 14:09
1
KUDOS
1
This post was
BOOKMARKED
bmwhype2 wrote:
The useful life of a certain piece of equipment is determined by the following formula: u =(8d)/h2, where u is the useful life of the equipment, in years, d is the density of the underlying material, in g/cm3, and h is the number of hours of daily usage of the equipment. If the density of the underlying material is doubled and the daily usage of the equipment is halved, what will be the percentage increase in the useful life of the equipment?

300%
400%
600%
700%
800%

I am assuming your question is u =(8d)/h^2,

Hence new equation would be
$$u_1 = \frac{8 * (2d)}{(\frac{h}{2})^2}$$ --> $$u_1 = 8 * \frac{8 * d} {({h})^2}$$ --> $$u_1 = 8*u$$

Hence 700% increase....
_________________

Stay Hungry, Stay Foolish

SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 147 [0], given: 2

Re: MGMAT - Formula [#permalink]

### Show Tags

20 Feb 2008, 18:01
agreed. assuming question is h^2, we have:

percentage change = u2-u1/u2 * 100

u1=8d/h^2

u2=[8*2d]/[(h/2)^2] -->64d/h^2

64d/h^2 - 8d/h^2 / 8d/h^2 = 7*100 = 700%
Director
Joined: 30 Jun 2007
Posts: 793
Followers: 1

Kudos [?]: 157 [0], given: 0

Re: MGMAT - Formula [#permalink]

### Show Tags

21 Feb 2008, 01:42
U = (8d) / h2 without any percentage change
D = 1 h = 1
Uold = 4
With change
Unew = 16d / h
D = 1 h = 1
Unew = 16

400%
Intern
Joined: 09 Jul 2013
Posts: 7
GMAT 1: 700 Q47 V39
Followers: 1

Kudos [?]: 15 [0], given: 23

Re: MGMAT - Formula [#permalink]

### Show Tags

27 Oct 2013, 04:17
hanumayamma wrote:
U = (8d) / h2 without any percentage change
D = 1 h = 1
Uold = 4
With change
Unew = 16d / h
D = 1 h = 1
Unew = 16

400%

Forgot to divide last h by 2 and then squared
Math Expert
Joined: 02 Sep 2009
Posts: 36548
Followers: 7077

Kudos [?]: 93127 [0], given: 10552

Re: The useful life of a certain piece of equipment is determine [#permalink]

### Show Tags

27 Oct 2013, 04:23
OPEN DISCUSSION OF THIS QUESTION IS HERE: the-useful-life-of-a-certain-piece-of-equipment-is-determine-101496.html
_________________
Re: The useful life of a certain piece of equipment is determine   [#permalink] 27 Oct 2013, 04:23
Similar topics Replies Last post
Similar
Topics:
4 The longevity of a certain metal construction is determined by the fol 3 03 Nov 2014, 09:01
12 In a certain game of dice, the player’s score is determined 7 13 Aug 2013, 20:39
8 At a certain car dealership, the 40 vehicles equipped with 9 13 Jul 2011, 08:08
7 In a certain sequence, every term after the first is determined by 3 15 Mar 2011, 21:59
3 The useful life of a certain piece of equipment is determine 11 22 Sep 2010, 05:25
Display posts from previous: Sort by

# The useful life of a certain piece of equipment is determine

 post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.