• NEW! FREE Beat The GMAT Quizzes
Hundreds of Questions Highly Detailed Reporting Expert Explanations
• 7 CATs FREE!
If you earn 100 Forum Points

Engage in the Beat The GMAT forums to earn
100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## If it takes 50 workers 8 hours to build . . . tagged by: M7MBA ##### This topic has 3 expert replies and 0 member replies ### Top Member ## If it takes 50 workers 8 hours to build . . . If it takes 50 workers 8 hours to build a log cabin, how long would it have taken 30 workers to build the same cabin? A) 9 hrs 36 min. B) 10 hrs 24 min. C) 12 hrs 24 min. D) 12 hrs 40 min. E) 13 hrs 20 min. The OA is E. Experts, how can I calculate the answer here? What formula should I state? ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2666 messages Followed by: 125 members Upvotes: 1153 GMAT Score: 770 M7MBA wrote: If it takes 50 workers 8 hours to build a log cabin, how long would it have taken 30 workers to build the same cabin? A) 9 hrs 36 min. B) 10 hrs 24 min. C) 12 hrs 24 min. D) 12 hrs 40 min. E) 13 hrs 20 min. The OA is E. Experts, how can I calculate the answer here? What formula should I state? If it takes 50 workers 8 hours to build a cabin, it takes a total of 50*8 = 400 worker-hours to complete the job. In other words, if # workers * # hours worked = 400, we've got ourselves a cabin. If there are 30 workers, we just need to solve 30 * # hours worked = 400 ---> # hours worked = 400/30 = 40/3 = 13 1/3 hours. The answer is E _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

### GMAT/MBA Expert

Legendary Member
Joined
14 Jan 2015
Posted:
2666 messages
Followed by:
125 members
1153
GMAT Score:
770
M7MBA wrote:
If it takes 50 workers 8 hours to build a log cabin, how long would it have taken 30 workers to build the same cabin?

A) 9 hrs 36 min.

B) 10 hrs 24 min.

C) 12 hrs 24 min.

D) 12 hrs 40 min.

E) 13 hrs 20 min.

The OA is E.

Experts, how can I calculate the answer here? What formula should I state?
Alternatively, the # of workers and # of hours worked will have a reciprocal relationship. (If we doubled the number of workers, they'd do the job in 1/2 the time, etc.)

If we started with 50 workers, then 30 workers would mean we'd have 30/50 = 3/5 the number of workers. So 3/5 the number of workers will do the job in 5/3 the time, which was initially 8 hours. (5/3) * 8 = 40/3 = 13 1/3. The answer is E

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! ### GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Hi M7MBA, Let's take a look at your question. The question states: "If it takes 50 workers 8 hours to build a log cabin, how long would it have taken 30 workers to build the same cabin? " 50 workers build a log cabin = 8 hours If we want to calculated how many hours will one worker take to build that cabin, we will be using the multiplication, since one worker will have to work more than 50 workers. Therefore, 1 worker will build the log cabin = 50 x 8 = 400 hours Now, we need to find out how many hours 30 workers will take to build the same log cabin. Since 30 workers are more than 1 worker, so they will take less time and hence we will be using the division to find the number of hours. 30 workers will build the log cabin = 400/30 = 13.33 hours. Therefore 30 workers will take 13.33 hours which means 13 complete hours and some more minutes. Let's see in the given options to find out the closest value to 13.33 hours i.e. 13 hours and 20 minutes. Therefore, Option E is correct. Hope it helps. I am available, if you'd like any follow up. _________________ GMAT Prep From The Economist We offer 70+ point score improvement money back guarantee. Our average student improves 98 points. Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now. • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

Available with Beat the GMAT members only code

• Award-winning private GMAT tutoring
Register now and save up to \$200

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Free Veritas GMAT Class
Experience Lesson 1 Live Free

Available with Beat the GMAT members only code

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

### Top First Responders*

1 Ian Stewart 41 first replies
2 Brent@GMATPrepNow 36 first replies
3 Scott@TargetTestPrep 33 first replies
4 Jay@ManhattanReview 30 first replies
5 GMATGuruNY 23 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

### Most Active Experts

1 Scott@TargetTestPrep

Target Test Prep

159 posts
2 Max@Math Revolution

Math Revolution

91 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

56 posts
4 Ian Stewart

GMATiX Teacher

50 posts
5 GMATGuruNY

The Princeton Review Teacher

35 posts
See More Top Beat The GMAT Experts