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

It is currently 21 Apr 2019, 17:29

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

If Robert can assemble a model car in 30 minutes and Craig

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

Hide Tags

 
General GMAT Forum Moderator
avatar
V
Joined: 29 Jan 2015
Posts: 1212
Location: India
WE: General Management (Non-Profit and Government)
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
If Robert can assemble a model car in 30 minutes and Craig  [#permalink]

Show Tags

New post 15 May 2017, 07:15
1
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

88% (00:55) correct 12% (01:28) wrong based on 49 sessions

HideShow timer Statistics

If Robert can assemble a model car in 30 minutes and Craig can assemble the same model car in 20 minutes, how long would it take them, working together, to assemble the model car?

(A) 12 minutes
(B) 13 minutes
(C) 14 minutes
(D) 15 minutes
(E) 16 minutes

_________________
If you liked my post, kindly give me a Kudos. Thanks.
CEO
CEO
User avatar
V
Joined: 12 Sep 2015
Posts: 3587
Location: Canada
Re: If Robert can assemble a model car in 30 minutes and Craig  [#permalink]

Show Tags

New post 15 May 2017, 07:44
Top Contributor
rohan2345 wrote:
If Robert can assemble a model car in 30 minutes and Craig can assemble the same model car in 20 minutes, how long would it take them, working together, to assemble the model car?

(A) 12 minutes
(B) 13 minutes
(C) 14 minutes
(D) 15 minutes
(E) 16 minutes


A quick approach is to assign a NICE VALUE to the job of assembling the model car.
Let's choose a value that works well with 30 minutes and 20 minutes.
How about 60.
So, let's say that the entire job consists of assembling 60 pieces.

Robert can assemble a model car in 30 minutes
Rate = output/time
= 60/30
= 2 pieces per minute

Craig can assemble the same model car in 20 minutes
Rate = output/time
= 60/20
= 3 pieces per minute

How long would it take them, working together, to assemble the model car?
Their COMBINED RATE = 2 + 3 = 5 pieces per minute
time = output/rate
= 60/5
= 12 minutes

Answer:

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
Image
Target Test Prep Representative
User avatar
P
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 5807
Location: United States (CA)
Re: If Robert can assemble a model car in 30 minutes and Craig  [#permalink]

Show Tags

New post 02 Apr 2019, 19:20
rohan2345 wrote:
If Robert can assemble a model car in 30 minutes and Craig can assemble the same model car in 20 minutes, how long would it take them, working together, to assemble the model car?

(A) 12 minutes
(B) 13 minutes
(C) 14 minutes
(D) 15 minutes
(E) 16 minutes


The combined rate of Robert and Craig is 1/20 + 1/30 = 3/60 + 2/60 = 5/60. We can interpret this rate as “They can assemble 5 model cars in 60 minutes.” Since time is the reciprocal of rate, it would take them 60/5 = 12 minutes to complete one car.

Answer: A
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

GMAT Club Bot
Re: If Robert can assemble a model car in 30 minutes and Craig   [#permalink] 02 Apr 2019, 19:20
Display posts from previous: Sort by

If Robert can assemble a model car in 30 minutes and Craig

  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®.