January 21, 2019 January 21, 2019 10:00 PM PST 11:00 PM PST Mark your calendars  All GMAT Club Tests are free and open January 21st for celebrate Martin Luther King Jr.'s Birthday. January 22, 2019 January 22, 2019 10:00 PM PST 11:00 PM PST In case you didn’t notice, we recently held the 1st ever GMAT game show and it was awesome! See who won a full GMAT course, and register to the next one.
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52339

Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
06 Oct 2014, 03:00
Question Stats:
77% (02:06) correct 23% (02:27) wrong based on 795 sessions
HideShow timer Statistics




SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1823
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
06 Oct 2014, 21:41
Rate of Adam = 50 tiles/hr Rate of Brianna = 60tiles/hr Combined rate = 105 tiles/hr Time required for 1400 tiles \(= \frac{1400}{105} = \frac{40}{3} = \frac{39}{3} + \frac{1}{3} *60 = 13 Hours 20 Minutes\) Answer = C
_________________
Kindly press "+1 Kudos" to appreciate




Current Student
Status: It always seems impossible until it's done!!
Joined: 29 Aug 2012
Posts: 1118
Location: India
WE: General Management (Aerospace and Defense)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
06 Oct 2014, 03:27
Bunuel wrote: Tough and Tricky questions: Work/Rate. Adam and Brianna plan to install a new tile floor in a classroom. Adam works at a constant rate of 50 tiles per hour, and Brianna works at a constant rate of 55 tiles per hour. If the new floor consists of exactly 1400 tiles, how long will it take Adam and Brianna working together to complete the classroom floor? A. 26 hrs. 44 mins. B. 26 hrs. 40 mins. C. 13 hrs. 20 mins. D. 13 hrs. 18 mins. E. 12 hrs. 45 mins. We need to find the individual time for Adam and Brianna to put the 1400 tiles. Adam: \(1400*\frac{1}{50}\)= 28 Hours. Brianna : \(1400*\frac{1}{55}\)=Mathematically it comes to 25.45. When we convert the decimal to time we get. 25 hours 27 Minutes. Now the combined rate, \(\frac{1}{A}\) + \(\frac{1}{B}\)= \(\frac{1}{28}\) + \(\frac{1}{25.45}\) = \(\frac{(25.45 + 28)}{(712.6)}\) = \(\frac{53.45}{712.6}\) Inverting this to get in hours. = \(\frac{712.6}{53.45}\) =13. 33 Converting it into hours ==> 13 hours 19.8 Minutes => 13 hours 20 Minutes. Answer is C. Bunuel: I hope you have some different approach to this problem. Please post your explanation.
_________________
Become a GMAT Club Premium member to avail lot of discounts



Senior Manager
Joined: 13 Jun 2013
Posts: 275

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
06 Oct 2014, 04:55
Gnpth wrote: Bunuel wrote: Tough and Tricky questions: Work/Rate. Adam and Brianna plan to install a new tile floor in a classroom. Adam works at a constant rate of 50 tiles per hour, and Brianna works at a constant rate of 55 tiles per hour. If the new floor consists of exactly 1400 tiles, how long will it take Adam and Brianna working together to complete the classroom floor? A. 26 hrs. 44 mins. B. 26 hrs. 40 mins. C. 13 hrs. 20 mins. D. 13 hrs. 18 mins. E. 12 hrs. 45 mins. We need to find the individual time for Adam and Brianna to put the 1400 tiles. Adam: \(1400*\frac{1}{50}\)= 28 Hours. Brianna : \(1400*\frac{1}{55}\)=Mathematically it comes to 25.45. When we convert the decimal to time we get. 25 hours 27 Minutes. Now the combined rate, \(\frac{1}{A}\) + \(\frac{1}{B}\)= \(\frac{1}{28}\) + \(\frac{1}{25.45}\) = \(\frac{(25.45 + 28)}{(712.6)}\) = \(\frac{53.45}{712.6}\) Inverting this to get in hours. = \(\frac{712.6}{53.45}\) =13. 33 Converting it into hours ==> 13 hours 19.8 Minutes => 13 hours 20 Minutes. Answer is C. Bunuel: I hope you have some different approach to this problem. Please post your explanation. actually we don't need to all these complex calculations w=1400 units when adam and briana work together, they will lay 55+50=105 tiles in an hour. therefore total time taken to lay 1400 tiles on the floor = 1400/105 = 40/3 hour =13(1/3) hour or 13 hour and (1/3)*60 minutes =13 hour and 20 minutes.



Intern
Joined: 04 Mar 2014
Posts: 10
Concentration: Marketing, General Management

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
04 Jan 2015, 00:43
PareshGmat wrote: Rate of Adam = 50 tiles/hr
Rate of Brianna = 60tiles/hr
Combined rate = 105 tiles/hr
Time required for 1400 tiles \(= \frac{1400}{105} = \frac{40}{3} = \frac{39}{3} + \frac{1}{3} *60 = 13 Hours 20 Minutes\)
Answer = C I usually go with " 1/A+1/B"... but this time I use strategy as you do. Are there any difference between 2 ways? THANKS



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1823
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
04 Jan 2015, 18:44
HuongShashi wrote: PareshGmat wrote: Rate of Adam = 50 tiles/hr
Rate of Brianna = 60tiles/hr
Combined rate = 105 tiles/hr
Time required for 1400 tiles \(= \frac{1400}{105} = \frac{40}{3} = \frac{39}{3} + \frac{1}{3} *60 = 13 Hours 20 Minutes\)
Answer = C I usually go with " 1/A+1/B"... but this time I use strategy as you do. Are there any difference between 2 ways? THANKS Rate = 1/Time Rates have to be combined to calculate the time required working together. In this problem, rate per hour is given directly. So the reciprocal addition does not come in picture
_________________
Kindly press "+1 Kudos" to appreciate



Director
Joined: 24 Nov 2015
Posts: 514
Location: United States (LA)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
02 Oct 2016, 05:35
Adam installs at a constant rate of 50 tiles per hour Brianna installs at a constant rate of 55 tiles per hour If both persons work together they can install 105 tiles in a hour Total number of installs to be done = 1400 time required for installation of 1400 tiles = \(\frac{1400}{105}\) = 13.3333 hrs = 13 hrs 20 mins Correct answer  C



Manager
Joined: 13 Aug 2015
Posts: 208
GPA: 3.82
WE: Corporate Finance (Retail Banking)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
27 May 2017, 04:48
Bunuel wrote: Tough and Tricky questions: Work/Rate. Adam and Brianna plan to install a new tile floor in a classroom. Adam works at a constant rate of 50 tiles per hour, and Brianna works at a constant rate of 55 tiles per hour. If the new floor consists of exactly 1400 tiles, how long will it take Adam and Brianna working together to complete the classroom floor? A. 26 hrs. 44 mins. B. 26 hrs. 40 mins. C. 13 hrs. 20 mins. D. 13 hrs. 18 mins. E. 12 hrs. 45 mins. W=R X T or, R=W/T Adam's Rate, A=50 tiles per hour Brianna's Rate, B=55 tiles per hour Combine rate (A+B) =50+55 =105 tiles per hour (We can ONLY ADD RATE of work in Work Rate problems) 105 tiles per hour 1 tile = 1/105 hour 1400 Tiles =1400/105 hour = 200/15 hours =40/3 hours =(39+1)/3 =39/3 + 1/3 hours =13 hours + 1/3 x 60 min =13 hours and 20 minutes Hence, Answer is:
_________________
If you like my posts, please give kudos. Help me unlock gmatclub tests.



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4342
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
27 May 2017, 08:04
Bunuel wrote: Tough and Tricky questions: Work/Rate. Adam and Brianna plan to install a new tile floor in a classroom. Adam works at a constant rate of 50 tiles per hour, and Brianna works at a constant rate of 55 tiles per hour. If the new floor consists of exactly 1400 tiles, how long will it take Adam and Brianna working together to complete the classroom floor? A. 26 hrs. 44 mins. B. 26 hrs. 40 mins. C. 13 hrs. 20 mins. D. 13 hrs. 18 mins. E. 12 hrs. 45 mins. \(\frac{1400}{(55+50)} = 13 \frac{1}{3}\) \(Hrs\) Thus, the correct answer must be (C)
_________________
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
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4557
Location: United States (CA)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
01 Jun 2017, 08:52
Quote: Adam and Brianna plan to install a new tile floor in a classroom. Adam works at a constant rate of 50 tiles per hour, and Brianna works at a constant rate of 55 tiles per hour. If the new floor consists of exactly 1400 tiles, how long will it take Adam and Brianna working together to complete the classroom floor?
A. 26 hrs. 44 mins. B. 26 hrs. 40 mins. C. 13 hrs. 20 mins. D. 13 hrs. 18 mins. E. 12 hrs. 45 mins.
Since Adam works at a constant rate of 50 tiles per hour and Brianna works at a constant rate of 55 tiles per hour, their combined rate is 105 tiles per hour. If we let t = the time they work together, we have: 105t = 1400 t = 1400/105 = 280/21 = 13 7/21 = 13 ⅓ hours = 13 hours 20 mins. Answer: C
_________________
Scott WoodburyStewart
Founder and CEO
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Senior Manager
Joined: 19 Oct 2012
Posts: 318
Location: India
Concentration: General Management, Operations
GMAT 1: 660 Q47 V35 GMAT 2: 710 Q50 V38
GPA: 3.81
WE: Information Technology (Computer Software)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
18 Sep 2017, 11:23
I am privileged to be among Super computers who solve this question within 1mins 20seconds. Guess I am too dumb to take close to 1min 45seconds to get through this!
_________________
Citius, Altius, Fortius



Manager
Joined: 22 Nov 2016
Posts: 208
Location: United States
Concentration: Leadership, Strategy
GPA: 3.4

Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
09 Nov 2017, 12:58
There is no need to find individual rates! We are already given that Adam and Brianna can lay tiles at the rate of 50 and 55 per hour.In 1 hour they will 105 tiles. 105 tiles  1 hour 1400 tiles \(\frac{1400}{105}\) \(\frac{14*100}{21*5}\) = \(\frac{14 * 20}{21}\) = \(\frac{7*2 * 20}{21}\) = \(\frac{40}{3}\) = 13.333 .333 = \(\frac{1}{3}\) and\(\frac{1}{3}\) of an hour is 20 minutes. Hence the answer is 13 hours and 20 minutes.
_________________
Kudosity killed the cat but your kudos can save it.



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 13361
Location: United States (CA)

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam
[#permalink]
Show Tags
08 Mar 2018, 10:43
Hi All, Although this question is presented in a "style" that is similar to a Work Formula question, it's actually just a Rate question.The rates can be combined into one big rate…. 50 tiles per hour + 55 tiles per hour = 105 tiles per hour You can now use the "Distance Formula" to answer this question…. D = R x T 1400 tiles = (105 tiles/hour)(Time) 1400/105 = Time 13 1/3 hours = T 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
CoFounder & 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!*****




Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam &nbs
[#permalink]
08 Mar 2018, 10:43






