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
GMATLiveTeach Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
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 Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget 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.

BTG-PQ "Pump A can empty a pool in A minutes, and pump

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Thu Jun 24, 2010 11:12 am
Thanked: 7 times
by gnod » Sat Jun 25, 2011 5:47 am
Please see attached image below: I understand the following (and feel free to correct me if i'm wrong)

Pump A empties Pool in A minutes
Pump B empties Pool in B minutes

so in 1 minute: A empties 1/A of pool
and in 1 minutes: B empties 1/B of pool

so if they started the same time, it would take:
1/A + 1/B = (A+B)/AB -> AB/(A+B) minutes to empty the pool.

BUT, since pump A started 1 minute earlier I had to find the time it would take for both pumps together would pump the same pool AB/(A+B) and multiply by how much of the pool was left after 1 minute of Pump A.

Here's where I get confused.

the explanation states that after 1 minute of Pump A, which is 1/A pumped out, there's (A-1)/A left.
I DON'T GET THIS PART! I feel like i'm missing something very basic.

Do I have to assume that since pumps A & B are pumping the same pool, we can say that the "pool" is "1"?

Seems like (A-1)/A = A/A - 1/A = 1 - 1/A
oy... i hope im not confusing anyone.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Thu Jun 24, 2010 11:12 am
Thanked: 7 times

by gnod » Sat Jun 25, 2011 5:48 am
Image


forgot image.

additionally, if someone has a much smarter, efficient way to solve this... i would take that over any day. but i'd still love to hear an answer to my specific question.

thank you!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1255
Joined: Fri Nov 07, 2008 2:08 pmFollowed by: 90 members
Location: St. Louis
Thanked: 312 times

by Tani » Sat Jun 25, 2011 7:58 am
Think of it in numbers. If A takes 10 minutes, after one minute there are nine minutes left. That's 9/10 of the original time or (10-1)/10 which is the same as (A-1)/A

In your scenario, that would be 1- 1/10, which is also equal to 9/10.
Tani Wolff
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 28
Joined: Thu Jun 24, 2010 11:12 am
Thanked: 7 times

by gnod » Sat Jun 25, 2011 2:58 pm
thank you.. that was easy enough. :D
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Sat Jun 25, 2011 3:42 pm
Pump A can empty a pool in A minutes, and pump B can empty the same pool in B minutes. Pump A begins emptying the pool for 1 minute before pump B joins. Beginning from the time pump A starts, how many minutes will it take to empty the pool?
Let pool = 6 units.
Let time for A = 2 minutes and time for B = 3 minutes.
Rate for A = w/t = 6/2 = 3 units per minute.
Rate for B = w/t = 6/3 = 2 units per minute.
Combined rate for A+B = 3+2 = 5 units per minute.
In 1 minute, A pumps out 3 units.
Remainder of pool = 6-3 = 3 units.
Time for A+B to finish = w/r = 3/5 minutes.
Total time = 1 + 3/5 = 8/5. This is our target.

Now we plug A=2 and B=3 into the answers to see which yields our target of 8/5.

Only answer choice B works:
A(B + 1)/ (A + B) = 2(3+1)/ (2+3) = 8/5.

The correct answer is B.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1