It is currently 20 Oct 2017, 20:56

### 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

# Adam and Brianna plan to install a new tile floor in a classroom. Adam

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 41892

Kudos [?]: 129048 [2], given: 12187

### Show Tags

06 Oct 2014, 04:00
2
KUDOS
Expert's post
12
This post was
BOOKMARKED
00:00

Difficulty:

25% (medium)

Question Stats:

77% (01:21) correct 23% (01:36) wrong based on 445 sessions

### HideShow timer Statistics

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.
[Reveal] Spoiler: OA

_________________

Kudos [?]: 129048 [2], given: 12187

Moderator
Status: It always seems impossible until it's done!!
Joined: 29 Aug 2012
Posts: 984

Kudos [?]: 1458 [2], given: 270

Location: India
GMAT 1: 680 Q47 V34
WE: General Management (Aerospace and Defense)

### Show Tags

06 Oct 2014, 04:27
2
KUDOS
1
This post was
BOOKMARKED
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.
_________________

Kudos [?]: 1458 [2], given: 270

Senior Manager
Joined: 13 Jun 2013
Posts: 278

Kudos [?]: 468 [6], given: 13

### Show Tags

06 Oct 2014, 05:55
6
KUDOS
2
This post was
BOOKMARKED
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.

Kudos [?]: 468 [6], given: 13

SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1853

Kudos [?]: 2626 [9], given: 193

Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

### Show Tags

06 Oct 2014, 22:41
9
KUDOS
2
This post was
BOOKMARKED
Rate of Adam = 50 tiles/hr

Rate of Brianna = 60tiles/hr

Combined rate = 105 tiles/hr

Time required for 1400 tiles $$= \frac{1400}{105} = \frac{40}{3} = \frac{39}{3} + \frac{1}{3} *60 = 13 Hours 20 Minutes$$

_________________

Kindly press "+1 Kudos" to appreciate

Kudos [?]: 2626 [9], given: 193

Intern
Joined: 04 Mar 2014
Posts: 12

Kudos [?]: 2 [0], given: 5

Concentration: Marketing, General Management

### Show Tags

04 Jan 2015, 01:43
PareshGmat wrote:
Rate of Adam = 50 tiles/hr

Rate of Brianna = 60tiles/hr

Combined rate = 105 tiles/hr

Time required for 1400 tiles $$= \frac{1400}{105} = \frac{40}{3} = \frac{39}{3} + \frac{1}{3} *60 = 13 Hours 20 Minutes$$

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

Kudos [?]: 2 [0], given: 5

SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1853

Kudos [?]: 2626 [1], given: 193

Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

### Show Tags

04 Jan 2015, 19:44
1
KUDOS
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 $$= \frac{1400}{105} = \frac{40}{3} = \frac{39}{3} + \frac{1}{3} *60 = 13 Hours 20 Minutes$$

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

Kudos [?]: 2626 [1], given: 193

Director
Joined: 24 Nov 2015
Posts: 586

Kudos [?]: 38 [1], given: 231

Location: United States (LA)

### Show Tags

02 Oct 2016, 06:35
1
KUDOS
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

Kudos [?]: 38 [1], given: 231

Manager
Joined: 13 Aug 2015
Posts: 205

Kudos [?]: 67 [0], given: 64

GMAT 1: 710 Q49 V38
GPA: 3.82
WE: Corporate Finance (Retail Banking)

### Show Tags

27 May 2017, 05:48
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
[Reveal] Spoiler:
C

_________________

If you like my posts, please give kudos. Help me unlock gmatclub tests.

Kudos [?]: 67 [0], given: 64

Math Forum Moderator
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3003

Kudos [?]: 1088 [0], given: 325

Location: India
GPA: 3.5

### Show Tags

27 May 2017, 09:04
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 )

Kudos [?]: 1088 [0], given: 325

Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 1648

Kudos [?]: 843 [1], given: 3

Location: United States (CA)

### Show Tags

01 Jun 2017, 09:52
1
KUDOS
Expert's post
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.

_________________

Scott Woodbury-Stewart
Founder and CEO

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

Kudos [?]: 843 [1], given: 3

Senior Manager
Joined: 19 Oct 2012
Posts: 324

Kudos [?]: 39 [0], given: 101

Location: India
Concentration: General Management, Operations
GMAT 1: 660 Q47 V35
GPA: 3.81
WE: Information Technology (Computer Software)

### Show Tags

18 Sep 2017, 12:23
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

Kudos [?]: 39 [0], given: 101

Re: Adam and Brianna plan to install a new tile floor in a classroom. Adam   [#permalink] 18 Sep 2017, 12:23
Display posts from previous: Sort by