BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
Vote for Target Test Prep, Newsweek Readers’ Choice Awards 2026
NEWSWEEK READERS’ CHOICE 2026

BIG NEWS! Target Test Prep has been nominated, and they’d love your vote!

TTP has worked incredibly hard to build the best test prep experience possible, and winning Newsweek’s 2026 Readers’ Choice Award for Best Test Prep would mean a lot to them. If TTP has helped you, they’d be incredibly grateful for your vote. You can vote once each day through September 9.

Vote for TTP
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

Question on combined work rates

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 490
Joined: Thu Jul 04, 2013 7:30 amFollowed by: 5 members
Location: Chennai, India
Thanked: 83 times

by Uva@90 » Mon Aug 26, 2013 7:20 pm
stephkhaira wrote:Each of 10 machines works at the same constant rate. Together they complete a job in 16 hours. How many hous does it take 8 machines to finish the job?

18
20
22
24
26

[spoiler]ans: 20[/spoiler]
Hi Stephkhaira,
Given: 10 machine takes 16 hours to complete a certain job.
To Find: How many hour does it take to complete same job using 8 machines.

Note: For these kind of problem we need to imagine some value( for example, here each machine produce one unit per hour)

Solution:
Ok, Let's imagine each machine produce One unit per hour.
therefore, 10*1*16=160.
So 10 machines produce 160 units of total in 16 hours.

Let X be no of hours for 8 machines to produce 160 Units.
In the same rate,
8*1*X =160

Hence X = 20

Regards,
Uva.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Mon Aug 26, 2013 9:32 pm
Hi stephkhaira,

Uva has explained a great, straight-forward approach to this question (it's the same way that I would solve this problem), so it's worth knowing.

As an aside, there's also a "ratio pattern" that's worth knowing:

You'll notice that in this question, the number of machines drops from 10 to 8; this is a 20% decrease. To end up with the same total output (in this case, the completed job), the way to offset the 20% decrease in machines is with a 25% increase in the other variable (in this case, the number of hours).

We start with 16 hours per machine; increasing this by 25% = 16 + 4 = 20 hours per machine.

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 643
Joined: Wed Aug 14, 2013 4:27 amFollowed by: 7 members
Thanked: 48 times

by vinay1983 » Wed Aug 28, 2013 6:47 am
I usually use the proportion method.

10 machines take 16 hours, 8 machines will take?

Notice that the no. of machines required for completion of the work have reduced, hence the no. of hours required will be more(Inverse proportion)

Machines time in hours

10 16


8 x

I.e x/16=10/8

x= 10/8*16=20

Hope this helps!
You can, for example never foretell what any one man will do, but you can say with precision what an average number will be up to!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 283
Joined: Sun Jun 23, 2013 11:56 pmFollowed by: 26 members
Location: Bangalore, India
Thanked: 97 times
GMAT Score:750

by ganeshrkamath » Wed Aug 28, 2013 10:21 am
stephkhaira wrote:Each of 10 machines works at the same constant rate. Together they complete a job in 16 hours. How many hous does it take 8 machines to finish the job?

18
20
22
24
26

[spoiler]ans: 20[/spoiler]
Let each machine take M hours to complete the work alone.
Rate of each machine = 1/M per hour
Rate of 10 machines = 10/M per hour
So the machines take M/10 hours to complete the work = 16 hours
M = 160

So 8 machines can finish the job in M/8 = 160/8 = 20 hours

Choose B

Cheers
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Kelley School of Business (Class of 2016)
GMAT Score: 750 V40 Q51 AWA 5 IR 8
https://www.beatthegmat.com/first-attemp ... tml#688494
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1