NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 14:18 It is currently 24 Apr 2024, 14:18
Decision Tracker
My Rewards
New posts
New comers' posts

Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

A particular parking garage is increasing its rates by 15 pe

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
tejal777
Senior Manager
Senior Manager
Joined: 25 Oct 2008
Posts: 361
Own Kudos [?]: 6508 [13]
Given Kudos: 100
Location: Kolkata,India
 Q44  V38
Send PM
A particular parking garage is increasing its rates by 15 pe [#permalink] New post   30 Oct 2009, 15:24
13
Bookmarks
00:00
A
B
C
D
E

Difficulty:

75% (hard)

Question Stats:

57% (02:23) correct 43% (02:36) wrong based on 377 sessions
Hide Show 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%
ShowHide Answer
Official Answer
D
Most Helpful Reply
User avatar
oldstudent
Intern
Intern
Joined: 20 Jun 2010
Status:Last few days....Have pressed the throttle
Posts: 40
Own Kudos [?]: 177 [21]
Given Kudos: 27
Concentration: Entrepreneurship,Strategy, Marketing
WE 1: 6 years - Consulting
Send PM
Re: parking garage [#permalink] New post   13 Aug 2010, 06:45
13
Kudos
8
Bookmarks
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!
General Discussion
User avatar
srini123
Manager
Manager
Joined: 13 Oct 2009
Affiliations: PMP
Posts: 153
Own Kudos [?]: 250 [4]
Given Kudos: 38
 Q48  V32
Send PM
Re: parking garage [#permalink] New post   30 Oct 2009, 15:52
3
Kudos
1
Bookmarks
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
User avatar
flgators519
Intern
Intern
Joined: 25 Oct 2009
Affiliations: University of Florida Alumni
Posts: 24
Own Kudos [?]: 20 [3]
Given Kudos: 11
Concentration: Finance
Schools:Wharton, Booth, Stanford, HBS
Send PM
Re: parking garage [#permalink] New post   30 Oct 2009, 16:48
3
Kudos
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
User avatar
hgp2k
Manager
Manager
Joined: 18 Aug 2009
Posts: 192
Own Kudos [?]: 773 [4]
Given Kudos: 13
 Q50  V35
Send PM
Re: parking garage [#permalink] New post   30 Oct 2009, 17:01
2
Kudos
2
Bookmarks
\(R*D=E\)
\(1.15R*(1-x)D=E\)
\(R*D=1.15R*(1-x)D\)
\(1-\frac{1}{1.15}=x\)

Solving, \(x=13%\)
avatar
SharpShark
Intern
Intern
Joined: 26 Oct 2009
Posts: 5
Own Kudos [?]: 2 [1]
Given Kudos: 13
Send PM
Re: parking garage [#permalink] New post   30 Oct 2009, 21:13
1
Kudos
I got 13 too, thanks sri and others for explanations
avatar
ricky2419
Intern
Intern
Joined: 10 Nov 2009
Posts: 7
Own Kudos [?]: 1 [1]
Given Kudos: 7
Send PM
Re: parking garage [#permalink] New post   17 Nov 2009, 04:19
1
Kudos
Let parking rate = 100

=(15/100+15)*100
=13.04%
avatar
fozzzy
Director
Director
Joined: 29 Nov 2012
Posts: 580
Own Kudos [?]: 6041 [0]
Given Kudos: 543
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   13 Jun 2013, 02:02
Plugging numbers is a better approach here or algebraic?
User avatar
jlgdr
VP
VP
Joined: 06 Sep 2013
Posts: 1345
Own Kudos [?]: 2391 [2]
Given Kudos: 355
Concentration: Finance
Schools: Wharton '17 (A) HBS '17 (WA$)
Send PM
GMAT ToolKit User
Re: parking garage [#permalink] New post   10 Oct 2013, 13:21
2
Bookmarks
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
avatar
Shree9975
Manager
Manager
Joined: 06 Mar 2014
Posts: 65
Own Kudos [?]: 58 [0]
Given Kudos: 3
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   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
User avatar
P
JeffTargetTestPrep
Target Test Prep Representative
Joined: 04 Mar 2011
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Posts: 3043
Own Kudos [?]: 6272 [0]
Given Kudos: 1646
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   02 Sep 2017, 07:23
Expert Reply
tejal777 wrote:
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%


We can let the per-month rate = p and the number of days in a month Bob uses the garage = n. We can also let x = the percentage decrease. Thus:

(1.15p)(n)((100-x/100) = np

(115/100)(100-x/100) = 1

(100-x/100) = 20/23

23(100-x) = 2000

2300 - 23x = 2000

300 = 23x

x ≈ 13

Answer: D
User avatar
B
gps5441
Manager
Manager
Joined: 04 May 2014
Posts: 114
Own Kudos [?]: 72 [1]
Given Kudos: 126
Location: India
WE:Sales (Mutual Funds and Brokerage)
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   11 Sep 2017, 03:51
1
Kudos
Formula
In case of increase use formula- \(\frac{r}{(100+r)}\)X100
In case of decrease use formula-\(\frac{r}{(100-r)}\)X100
r is the percentage change.

Now to the question

r is the % increase

\(\frac{15}{(100+15)}\)X100=\(\frac{1500}{115}\)=13%
User avatar
S
Sushen
Manager
Manager
Joined: 29 Dec 2019
Posts: 57
Own Kudos [?]: 35 [1]
Given Kudos: 38
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   25 Jan 2022, 12:11
1
Kudos
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, \(x=13%\)



What do your variables stand for?
User avatar
D
desertEagle
Director
Director
Joined: 14 Jun 2014
Posts: 582
Own Kudos [?]: 301 [0]
Given Kudos: 413
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   25 Jan 2022, 12:42
Sushen wrote:
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, \(x=13%\)



What do your variables stand for?


Total Cost = Price x Day = constant

if we increase price by 15%, then new price will be (1 +15/100) = 115/100
In order to keep total Cost same i.e. constant we will have to reduce day by a factor of 100/115.

115/100 Price X 100/115 Days = Price X Day = constant

Thus Days will reduce by (1-100/115) = 15/115
i.e. 15/115x100 = 13 %
User avatar
D
desertEagle
Director
Director
Joined: 14 Jun 2014
Posts: 582
Own Kudos [?]: 301 [0]
Given Kudos: 413
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   25 Jan 2022, 12:44
Sushen wrote:
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, \(x=13%\)



What do your variables stand for?


R stands for Rate
D stands for Days
E stands for Expenditure
x stands for fraction dreacrese in Days
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 32655
Own Kudos [?]: 821 [0]
Given Kudos: 0
Send PM
Re: A particular parking garage is increasing its rates by 15 pe [#permalink] New post   16 Jan 2024, 12:14
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.
GMAT Club Bot
gmatclubot
Re: A particular parking garage is increasing its rates by 15 pe [#permalink]
16 Jan 2024, 12:14
Moderators:
Bunuel
Math Expert
92902 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions