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

 It is currently 26 Aug 2016, 05:53

### 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

# A particular parking garage is increasing its rates by 15 pe

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

### Hide Tags

Director
Joined: 25 Oct 2008
Posts: 607
Location: Kolkata,India
Followers: 11

Kudos [?]: 646 [0], given: 100

A particular parking garage is increasing its rates by 15 pe [#permalink]

### Show Tags

30 Oct 2009, 15:24
2
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

58% (02:52) correct 42% (02:02) wrong based on 203 sessions

### HideShow timer Statistics

A particular parking garage is increasing its rates by 15 percent per month. Bob decides to reduce the number of days he uses the garage per month so that the amount he spends at the garage per month remains unchanged. Which of the following is closest to Bob’s percentage reduction in the number of days he uses the garage each month?

A. 10%
B. 11%
C. 12%
D. 13%
E. 14%
[Reveal] Spoiler: OA

_________________

http://gmatclub.com/forum/countdown-beginshas-ended-85483-40.html#p649902

Senior Manager
Affiliations: PMP
Joined: 13 Oct 2009
Posts: 312
Followers: 4

Kudos [?]: 148 [2] , given: 37

Re: parking garage [#permalink]

### Show Tags

30 Oct 2009, 15:52
2
KUDOS
1
This post was
BOOKMARKED
is 13% the answer?

let m be the rate per month , then 1.15m is the rate per month after increase

let d be the number of days he used garage, then total cost assuming 30 days in month = md/30

let n be days to be reduced to remain at same cost, so we get

we need to find n*100/d

md/30 = 1.15m (d-n)/30

==>

d = 1.15(d-n)

divide both sides by d ==>
1 = 1.15 - 1.15n/d
==>1.15n/d = .15
==>100n/d = 15/1.15 = 13
_________________

Thanks, Sri
-------------------------------
keep uppp...ing the tempo...

Press +1 Kudos, if you think my post gave u a tiny tip

Intern
Affiliations: University of Florida Alumni
Joined: 25 Oct 2009
Posts: 36
Schools: Wharton, Booth, Stanford, HBS
Followers: 0

Kudos [?]: 14 [0], given: 11

Re: parking garage [#permalink]

### Show Tags

30 Oct 2009, 16:48
Assuming Current Cost of $1, next month it will cost$1.15 for same services

X * 1.15 = $1 with X being the percentage of full previous services X = 86.956% so you must use roughly 13% less at the higher rate to keep your costs the same. Note if it asked you in Month 3 or X amount of decrease, you would just compound this rate. Ex. .86956 ^2 = Usage in Month 3 or just 1 / 1.15^2 _________________ Kudos are greatly appreciated and I'll always return the favor on one of your posts. Thanks! Senior Manager Joined: 18 Aug 2009 Posts: 328 Followers: 8 Kudos [?]: 267 [1] , given: 13 Re: parking garage [#permalink] ### Show Tags 30 Oct 2009, 17:01 1 This post received KUDOS 1 This post was BOOKMARKED $$R*D=E$$ $$1.15R*(1-x)D=E$$ $$R*D=1.15R*(1-x)D$$ $$1-\frac{1}{1.15}=x$$ Solving, $$x=13%$$ Intern Joined: 26 Oct 2009 Posts: 11 Followers: 0 Kudos [?]: 1 [1] , given: 13 Re: parking garage [#permalink] ### Show Tags 30 Oct 2009, 21:13 1 This post received KUDOS I got 13 too, thanks sri and others for explanations Intern Joined: 10 Nov 2009 Posts: 7 Followers: 0 Kudos [?]: 0 [0], given: 7 Re: parking garage [#permalink] ### Show Tags 17 Nov 2009, 04:19 Let parking rate = 100 =(15/100+15)*100 =13.04% Manager Status: Last few days....Have pressed the throttle Joined: 20 Jun 2010 Posts: 71 WE 1: 6 years - Consulting Followers: 3 Kudos [?]: 42 [8] , given: 27 Re: parking garage [#permalink] ### Show Tags 13 Aug 2010, 06:45 8 This post received KUDOS 2 This post was BOOKMARKED Best way to solve such Questions: Remember - If Value of an item goes UP by x%, then the REDUCTION to be made to bring it to original value is calculated by formula: x*100/(100+x)% If Value of an item goes DOWN by x%, then the INCREMENT to be made to bring it to original value is calculated by formula: x*100/(100-x)% Hope this helps! _________________ Consider giving Kudos if my post helps in some way Director Joined: 29 Nov 2012 Posts: 900 Followers: 14 Kudos [?]: 873 [0], given: 543 Re: A particular parking garage is increasing its rates by 15 pe [#permalink] ### Show Tags 13 Jun 2013, 02:02 Plugging numbers is a better approach here or algebraic? _________________ Click +1 Kudos if my post helped... Amazing Free video explanation for all Quant questions from OG 13 and much more http://www.gmatquantum.com/og13th/ GMAT Prep software What if scenarios http://gmatclub.com/forum/gmat-prep-software-analysis-and-what-if-scenarios-146146.html Current Student Joined: 06 Sep 2013 Posts: 2035 Concentration: Finance GMAT 1: 770 Q0 V Followers: 54 Kudos [?]: 514 [0], given: 355 Re: parking garage [#permalink] ### Show Tags 10 Oct 2013, 13:21 hgp2k wrote: $$R*D=E$$ $$1.15R*(1-x)D=E$$ $$R*D=1.15R*(1-x)D$$ $$1-\frac{1}{1.15}=x$$ Solving, $$x=13%$$ This is the best approach. Always try to use 1 if possible. Makes lifes easier Manager Joined: 13 Aug 2012 Posts: 118 Followers: 0 Kudos [?]: 49 [0], given: 118 Re: A particular parking garage is increasing its rates by 15 pe [#permalink] ### Show Tags 11 Oct 2013, 08:07 Can someone help me here? I did it by the following method but the ans is coming out to be wrong So let the original rate be 100$ and assuming that the no of days for that month is 30, The Per day rate comes out to be $$\frac{100}{30}=\frac{10}{3}$$
Now the rate increases 15 percent per month, so the the next month's rate would be 115$. The per day rate comes out to be $$\frac{115}{30}$$. So what i did was that let the no of days in the new month that would equate to 100$ be x. The equation comes out to be
$$\frac{115x}{30}=100$$
$$x=\frac{3000}{115} days$$

The percentage change would be $$[30-(3000/115)]/30$$$$\approx{10%}$$
What am i doing wrong?
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11068
Followers: 511

Kudos [?]: 134 [0], given: 0

Re: A particular parking garage is increasing its rates by 15 pe [#permalink]

### Show Tags

08 Jul 2015, 02:58
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Manager
Joined: 06 Mar 2014
Posts: 103
Followers: 1

Kudos [?]: 7 [0], given: 3

Re: A particular parking garage is increasing its rates by 15 pe [#permalink]

### Show Tags

27 Jul 2015, 10:30
jlgdr
hgp2k

What is x in ur solution.
And how can it be(1-x), how can u subtract 1- number of days???

Thanks
Re: A particular parking garage is increasing its rates by 15 pe   [#permalink] 27 Jul 2015, 10:30
Similar topics Replies Last post
Similar
Topics:
The cost to park a car in a certain parking garage is $8.00 2 12 Jan 2016, 06:26 1 A parking garage rents parking spaces for$10 per week or \$30 per 1 29 Nov 2015, 10:59
3 A certain telescope increases the visual range at a particular locatio 3 26 Nov 2015, 06:04
If the sides of a rectangle are increased by 15% 2 20 Feb 2013, 22:37
11 A parking garage has places for a certain number of cars. If 10 17 Sep 2010, 01:05
Display posts from previous: Sort by

# A particular parking garage is increasing its rates by 15 pe

 new topic 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®.