GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 19 Oct 2018, 06:21

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.

Close

Request Expert Reply

Confirm Cancel

Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i

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

Hide Tags

Retired Moderator
avatar
Joined: 29 Apr 2015
Posts: 848
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
GMAT ToolKit User Premium Member
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 15 May 2015, 03:11
8
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

66% (02:11) correct 34% (02:20) wrong based on 208 sessions

HideShow timer Statistics

Brian has to clean 675 beer glasses. If he cleans 16% of the glasses in the first 88 minutes, then which of the following is closest to the number of hours Brian has to work at double his initial speed, to finish cleaning the rest of the glasses?

A. 4.1
B. 7.8
C. 8
D. 8.2
E. 3.9

_________________

Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.

Most Helpful Expert Reply
e-GMAT Representative
User avatar
P
Joined: 04 Jan 2015
Posts: 2069
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 15 May 2015, 05:15
3
2
Hi reto,

Presenting the detailed solution below:

Given
We are given the initial rate at which Brian works and are asked to find the time taken by Brian to complete the rest of the work at double his initial rate.

Approach
We know that Work = Rate * Time. Since we are given the initial amount of work done we can find out the balance amount of work to be done(i.e. cleaning the glasses). Also we know the initial rate of Brian which can be used to calculate his final rate to do the work. Since we know the amount of work to be done and the rate at which Brian will be working, we can find out the time taken by him.

Working Out
Initial no. of glasses cleaned by Brian = 16% of 675 = \(\frac{16}{100} * 675\)

Time taken by Brian for cleaning glasses = 88 minutes

Brian's rate of cleaning glasses \(=\frac{16*675}{100*88}\) glasses/minute


His rate for cleaning the remaining glasses = 2 * Initial Rate = \(2 * \frac{16*675}{100*88}\)

Number of remaining glasses to be cleaned = (100-16)% of 675 glasses = \(\frac{84}{100} * 675\)

Time taken by Brian to clean the remaining glasses \(= \frac{84}{100} * 675 * \frac{100* 88}{16* 675 * 2}\) = 231 minutes = ~ 3.9 hours

Hope its clear :)

Regards
Harsh
_________________








Register for free sessions
Number Properties | Algebra |Quant Workshop

Success Stories
Guillermo's Success Story | Carrie's Success Story

Ace GMAT quant
Articles and Question to reach Q51 | Question of the week

Must Read Articles
Number Properties – Even Odd | LCM GCD | Statistics-1 | Statistics-2
Word Problems – Percentage 1 | Percentage 2 | Time and Work 1 | Time and Work 2 | Time, Speed and Distance 1 | Time, Speed and Distance 2
Advanced Topics- Permutation and Combination 1 | Permutation and Combination 2 | Permutation and Combination 3 | Probability
Geometry- Triangles 1 | Triangles 2 | Triangles 3 | Common Mistakes in Geometry
Algebra- Wavy line | Inequalities

Practice Questions
Number Properties 1 | Number Properties 2 | Algebra 1 | Geometry | Prime Numbers | Absolute value equations | Sets



| '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com

General Discussion
Manager
Manager
avatar
S
Joined: 13 Nov 2014
Posts: 112
GMAT 1: 740 Q50 V40
Reviews Badge
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 15 May 2015, 08:09
reto wrote:
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses in the first 88 minutes, then which of the following is closest to the number of hours Brian has to work at double his initial speed, to finish cleaning the rest of the glasses?

A. 4.1
B. 7.8
C. 8
D. 8.2
E. 3.9



is this really a sub 600? I got it right but the calculations took me just over 3 mins. The process is very simple, but the numbers are not the best.
_________________

Gmat prep 1 600
Veritas 1 650
Veritas 2 680
Gmat prep 2 690 (48Q 37V)
Gmat prep 5 730 (47Q 42V)
Gmat prep 6 720 (48Q 41V)

Retired Moderator
avatar
Joined: 29 Apr 2015
Posts: 848
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
GMAT ToolKit User Premium Member
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 15 May 2015, 08:47
Wofford09 wrote:
reto wrote:
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses in the first 88 minutes, then which of the following is closest to the number of hours Brian has to work at double his initial speed, to finish cleaning the rest of the glasses?

A. 4.1
B. 7.8
C. 8
D. 8.2
E. 3.9



is this really a sub 600? I got it right but the calculations took me just over 3 mins. The process is very simple, but the numbers are not the best.


Im actually not sure what level it is because it was not stated. I would try like that:

Brian's rate of cleaning glasses is \(=\frac{0.16*675}{88}\) glasses/minute
For the remaining glasses he has the double rate: \(2 * \frac{0.16*675}{88}\)

Now all you have to do is divide the remaining classes through the new double rate (don't calculate the exact number but use 0.84*675 for the remaining glasses) like that:

\(\frac{0.84*675*88}{2*0.16*675}\)

Then cancel out as much terms as possible (675 cancels, 88 cancels with the 2 in the denominator and 0.84 divided with 0.16 is approx 5 times). This leaves you with a nice approximation of 5*44 minutes = 220min = 3.6 hours. I think that should be enough.

If you want to be more precise look at the solution from EgmatQuantExpert and do it with the whole percent numbers.

Does this help?
_________________

Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.

e-GMAT Representative
User avatar
P
Joined: 04 Jan 2015
Posts: 2069
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 15 May 2015, 11:17
1
Wofford09 wrote:
reto wrote:
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses in the first 88 minutes, then which of the following is closest to the number of hours Brian has to work at double his initial speed, to finish cleaning the rest of the glasses?

A. 4.1
B. 7.8
C. 8
D. 8.2
E. 3.9



is this really a sub 600? I got it right but the calculations took me just over 3 mins. The process is very simple, but the numbers are not the best.


Hi Wofford09,

You do not need to do the calculations at every step. Such questions also tests how well you interpret numbers. If you avoid calculations till the last step you would get the fraction as \(\frac{84}{100} * 675 * \frac{100* 88}{16* 675 * 2}\).

The larger terms would cancel out to give you a straightforward fraction \(\frac{84*88}{16*2} = 21 * 11 = 231\) minutes.

The numbers are given in a manner so that it cancels out at the end and the calculation becomes pretty straightforward.

Hope this helps :)

Regards
Harsh
_________________








Register for free sessions
Number Properties | Algebra |Quant Workshop

Success Stories
Guillermo's Success Story | Carrie's Success Story

Ace GMAT quant
Articles and Question to reach Q51 | Question of the week

Must Read Articles
Number Properties – Even Odd | LCM GCD | Statistics-1 | Statistics-2
Word Problems – Percentage 1 | Percentage 2 | Time and Work 1 | Time and Work 2 | Time, Speed and Distance 1 | Time, Speed and Distance 2
Advanced Topics- Permutation and Combination 1 | Permutation and Combination 2 | Permutation and Combination 3 | Probability
Geometry- Triangles 1 | Triangles 2 | Triangles 3 | Common Mistakes in Geometry
Algebra- Wavy line | Inequalities

Practice Questions
Number Properties 1 | Number Properties 2 | Algebra 1 | Geometry | Prime Numbers | Absolute value equations | Sets



| '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com

EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12676
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 15 May 2015, 15:29
1
1
Hi reto,

This question can be solved with a bit of estimation and some basic calculations.

To start, the fact that there are 675 beer glasses is actually irrelevant.

We know that Brian cleaned 16% of the glasses in 88 minutes. That's about 1/6 of the glasses in about 1.5 hours.

To clean the remaining 5/6 of the glasses at this same rate would take about 5(1.5) = 7.5 hours....

HOWEVER, we're told that Brian will work at DOUBLE his initial rate, so we have to divide that time in HALF:

7.5/2 = 3.75 hours

Now, given that 16% is NOT exactly 1/6 and that 88 minutes is LESS than 1.5 hours, our estimate is pretty close....

Final Answer:

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****

Senior Manager
Senior Manager
User avatar
G
Joined: 03 Apr 2013
Posts: 280
Location: India
Concentration: Marketing, Finance
GMAT 1: 740 Q50 V41
GPA: 3
GMAT ToolKit User
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 28 May 2016, 04:37
1
There's a simple way to go about it. First, as the question is all about Percentages, forget about the number of glasses. We will use percentages and the good old unitary method to do this.

Lets start :)

Point 1

16% in 88 mins at normal speed.
So, at double the speed...? it will take half the time to do the same work

Thus, at double speed --> 16% in 44 mins.

Point 2

Work already done --> 16%
Work left --> 100-16 --> 84% (and this has to be done at double the speed)

Applying unitary method

\(16%\) ---------- \(44 mins\)

\(1%\) ------------ \(\frac{44}{16}\)

\(84%\) ---------- \(\frac{44}{16} * 84\)

Converting the above result into hours by dividing by 60 will give you the answer as 3.85...which is closest to 3.9 and Voila :)


_________________

Spread some love..Like = +1 Kudos :)

Board of Directors
User avatar
P
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4094
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 24 Jul 2017, 08:32
reto wrote:
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses in the first 88 minutes, then which of the following is closest to the number of hours Brian has to work at double his initial speed, to finish cleaning the rest of the glasses?

A. 4.1
B. 7.8
C. 8
D. 8.2
E. 3.9


In 88 mins Brian cleans \(108\) beer glasses...
In 1 min Brian cleans \(\frac{108}{88}\) beer glasses...

Twice initial efficiency is \(\frac{108}{88}\) \(*2\) = \(\frac{108}{44}\) glasses...

Glasses remaining is \(675 - 108 = 567\)

Time required to clean those is \(\frac{567*44}{108*60}\) = \(3.85\) Hours

Thus, the answer must be (E) 3.9 Hours...
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Target Test Prep Representative
User avatar
P
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 3886
Location: United States (CA)
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 26 Jul 2017, 16:39
reto wrote:
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses in the first 88 minutes, then which of the following is closest to the number of hours Brian has to work at double his initial speed, to finish cleaning the rest of the glasses?

A. 4.1
B. 7.8
C. 8
D. 8.2
E. 3.9


We are given that Brian has to clean 675 beer glasses. If Brian cleans 16% (or 0.16 x 675 = 108) of them in 88 minutes, his rate in minutes is 108/88 = 27/22. If his speed is doubled, his new rate is 54/22 = 27/11. Since he has 567 glasses left to clean, the time in minutes is:

567/(27/11) = (567 x 11)/27 = 21 x 11 = 231 minutes or 231/60 = 3.85 hours.

Answer: E
_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Manager
Manager
avatar
G
Joined: 14 Oct 2012
Posts: 167
Premium Member Reviews Badge
Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 30 Jul 2017, 09:48
My 2 cents -

NOTE - 21/60 ~ 1/3 because we can approximate it as 20/60 = 1/3.
Attachments

my 2 cents.jpg
my 2 cents.jpg [ 22.92 KiB | Viewed 847 times ]

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 8464
Premium Member
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i  [#permalink]

Show Tags

New post 24 Sep 2018, 10:07
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 Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

GMAT Club Bot
Re: Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i &nbs [#permalink] 24 Sep 2018, 10:07
Display posts from previous: Sort by

Brian has to clean 675 beer glasses. If he cleans 16% of the glasses i

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.