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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Engine A can work 5 hours on 10 liters of fuel

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 366
Joined: Fri Jun 05, 2015 3:35 amFollowed by: 2 members
Thanked: 3 times
by NandishSS » Fri Sep 08, 2017 8:23 am
Engine A can work 5 hours on 10 liters of fuel while engine B can work 3 hours on 15 liters of fuel. If engine efficiency is defined as a reciprocal to the hourly fuel consumption rate, what is the ratio of the efficiency of engine B to that of engine A?

A)2/5
B)1/2
C)2
D)5/2
E)3

OA: A

What is hourly fuel consumption rate ?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 amFollowed by: 128 members
Location: Boston, MA
Thanked: 1153 times
GMAT Score:770

by DavidG@VeritasPrep » Fri Sep 08, 2017 9:08 am
NandishSS wrote:Engine A can work 5 hours on 10 liters of fuel while engine B can work 3 hours on 15 liters of fuel. If engine efficiency is defined as a reciprocal to the hourly fuel consumption rate, what is the ratio of the efficiency of engine B to that of engine A?

A)2/5
B)1/2
C)2
D)5/2
E)3

OA: A

What is hourly fuel consumption rate ?
You can think of any rate as "task/time period." So here the fuel consumption rate for A is 10 liters/5 hours = 2 liters/hour and the consumption rate for B is 15 liters/3hours = 5 liters per hours.

If the engine efficiency is the reciprocal of this figure, then the engine efficiency for A is 1/2 and for B it's 1/5.

We want the ratio of the efficiency of B to the efficiency of A, or (1/5)/(1/2) = 1/5 * 2/1 = 2/5. The answer is A
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 amFollowed by: 128 members
Location: Boston, MA
Thanked: 1153 times
GMAT Score:770

by DavidG@VeritasPrep » Fri Sep 08, 2017 9:10 am
Note, also, that it's often the case that a question will have both the correct answer and a trap answer among the answer choices. In this case, because we're dealing with reciprocals, it stands to reason that there's a good chance 2/5 and 5/2 represent a correct answer and a trap. (Of course, there are exceptions.) If you're able to see that B's engine efficiency is less than that of A's, you can jump right to the answer almost immediately.
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 amFollowed by: 34 members
Location: Grand Central / New York
Thanked: 470 times

by Jay@ManhattanReview » Sat Sep 09, 2017 12:47 am
NandishSS wrote:Engine A can work 5 hours on 10 liters of fuel while engine B can work 3 hours on 15 liters of fuel. If engine efficiency is defined as a reciprocal to the hourly fuel consumption rate, what is the ratio of the efficiency of engine B to that of engine A?

A)2/5
B)1/2
C)2
D)5/2
E)3

OA: A

What is hourly fuel consumption rate ?
"Hourly fuel consumption rate" means the amount of fuel consumed in an hour measured in Liter per hour

Thus, efficiency = Reciprocal of (Liter per hour) = Hour per liter

Hope this helps!

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide

-Jay
_________________
Manhattan Review GMAT Prep

Locations: New York | Jakarta | Nanjing | Berlin | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8151
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

Re: Engine A can work 5 hours on 10 liters of fuel

by Scott@TargetTestPrep » Sun Feb 09, 2020 5:38 am
NandishSS wrote: ↑
Fri Sep 08, 2017 8:23 am
 Engine A can work 5 hours on 10 liters of fuel while engine B can work 3 hours on 15 liters of fuel. If engine efficiency is defined as a reciprocal to the hourly fuel consumption rate, what is the ratio of the efficiency of engine B to that of engine A?

A)2/5
B)1/2
C)2
D)5/2
E)3

OA: A

What is hourly fuel consumption rate ?
Engine A’s fuel consumption is 10/5 = 2 liters per hour.

Engine B’s fuel consumption is 15/3 = 5 liters per hour.

Since engine efficiency is the reciprocal of the hourly fuel consumption rate, then the engine efficiency of A is 1/2, and the efficiency of B is 1/5.

Thus, the ratio of B’s efficiency to that of A is (1/5) / (1/2) = 2/5.

Answer: A

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1