by: jeffn
19 mins
by: DensePan
32 mins
Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Sep 1507:00 PM EDT
-09:00 PM EST
Elite scores are possible when you enroll in a powerful GMAT course, taught live online + 6 months access to TTP OnDemand video courses included! Class starts Tues/Thurs Sept. 15, 2026 - Nov. 15, 2027, 7:00pm-9:00pm EST
Sep 2107:00 PM EDT
-10:00 PM EDT
Boost your GMAT score in less than one month in a live online class + 6 months access to TTP OnDemand video courses included! Class starts Mon, Tues, Wed, Thur, Fri Sept. 21, 2026 - Oct. 9, 2027, 7:00pm-10:00pm EST
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
83% (02:40) correct
17%
(02:31)
wrong
based on 120
sessions
History
Date
Time
Result
Not Attempted Yet
A piece of work can be done by Ram and Shyam in 12 days, by Shyam and Hari in 15 days and by Hari and Ram in 20 days. Ram alone will complete the work in how many days?
A. 35
B. 32
C. 30
D. 28
E. 25
_________________
A. 35
B. 32
C. 30
D. 28
E. 25
_________________
New to the GMAT Club?
- • Questions: Question Bank | Bunuel's Signature Collection
• Tests: GMAT Club Tests | Forum Quiz
• Guides: Quantitative | Critical Reasoning | Reading Comprehension | Ultimate Quant Guide | All You Need for Quant
• Rules: Quantitative | Verbal
TestPrepUnlimited
Expert
Tutor
Joined: 16 Sep 2014
Last visit: 30 Jun 2022
Posts: 1,221
Location: United States
GMAT 1: 780 Q51 V45
GRE 1: Q170 V167
Expert reply
Set R, S, and H as the respective rates.
Then we have R + S = 1/12, S + H = 1/15, H + R = 1/20.
We want to solve for R, we can eliminate S first by subtracting the first two equations with each other:
R - H = 1/12 - 1/15 = (15 - 12) / (12*15) = 3 / (12*15) = 1/60.
We also have R + H = 1/20.
Add these two equations to get: 2R = 1/60 + 1/20 = 1/60 + 3/60 = 4/60 = 1/15.
R = 1/30, so it would take R 30 days to complete the task alone.
Ans: C
_________________
Then we have R + S = 1/12, S + H = 1/15, H + R = 1/20.
We want to solve for R, we can eliminate S first by subtracting the first two equations with each other:
R - H = 1/12 - 1/15 = (15 - 12) / (12*15) = 3 / (12*15) = 1/60.
We also have R + H = 1/20.
Add these two equations to get: 2R = 1/60 + 1/20 = 1/60 + 3/60 = 4/60 = 1/15.
R = 1/30, so it would take R 30 days to complete the task alone.
Ans: C
_________________
Source: We are an NYC based, in-person and online GMAT tutoring and prep company. We are the only GMAT provider in the world to guarantee specific GMAT scores with our flat-fee tutoring packages, or to publish student score increase rates. Our typical new-to-GMAT student score increase rate is 3-9 points per tutoring hour, the fastest in the world. !
Quote:
(1/r+1/s)=1/12 - (1/s+1/h)=1/15
1/r-1/h=1/12-1/15
1/r-1/h=1/60;
1/r-1/h=1/60 + (1/r+1/h)=1/20
2/r=1/60+1/20
2/r=1/15
r=30
Ans (C)
GMAT 1: 720 Q49 V40
Posts: 939
Let r, s, h be the days required to complete a piece of works by Ram, Shyam, Hari, respectively.
(1/r + 1/s) -(1/s + 1/h) +(1/h + 1/r) = 1/12 -1/15 +1/20
1/r + 1/r = 2/r = 5/60 -4/60 +3/60 = 4/60
--> r =30 days
FINAL ANSWER IS (C)
Posted from my mobile device
(1/r + 1/s) -(1/s + 1/h) +(1/h + 1/r) = 1/12 -1/15 +1/20
1/r + 1/r = 2/r = 5/60 -4/60 +3/60 = 4/60
--> r =30 days
FINAL ANSWER IS (C)
Posted from my mobile device
\(\frac{1}{r}+ \frac{1}{s}= \frac{1}{12}\)
\(\frac{1}{s} + \frac{1}{h}= \frac{1}{15}\)
\(\frac{1}{r} +\frac{1}{h} = \frac{1}{20}\)
—> adding all together:
\(2( \frac{1}{r}+ \frac{1}{s}+ \frac{1}{h}) = \frac{1}{12}+ \frac{1}{15}+\frac{1}{20}\)
\(\frac{1}{r}+ \frac{1}{s}+\frac{1}{h}= \frac{1}{10}\)
\(\frac{1}{r} = \frac{1}{10}–( \frac{1}{s}+ \frac{1}{h}) = \frac{1}{10}–\frac{1}{15}\)
—> \(\frac{1}{r} = \frac{1}{30}\)
r = 30
The answer is C
Posted from my mobile device
\(\frac{1}{s} + \frac{1}{h}= \frac{1}{15}\)
\(\frac{1}{r} +\frac{1}{h} = \frac{1}{20}\)
—> adding all together:
\(2( \frac{1}{r}+ \frac{1}{s}+ \frac{1}{h}) = \frac{1}{12}+ \frac{1}{15}+\frac{1}{20}\)
\(\frac{1}{r}+ \frac{1}{s}+\frac{1}{h}= \frac{1}{10}\)
\(\frac{1}{r} = \frac{1}{10}–( \frac{1}{s}+ \frac{1}{h}) = \frac{1}{10}–\frac{1}{15}\)
—> \(\frac{1}{r} = \frac{1}{30}\)
r = 30
The answer is C
Posted from my mobile device
QuantMadeEasy
Joined: 27 Feb 2014
Last visit: 01 Mar 2026
Posts: 502
Location: India
Concentration: General Management, International Business
GPA: 3.97
WE:Engineering (Education)
Posts: 502
rate of (R+S) = 1/12 ----(i)
rate of (S+H) = 1/15 ---- (ii)
rate of (H+R) = 1/20 -----(iii)
rate of (R+S+H) = 1/10 ----(iv)
rate of R = 1/10 - 1/15 = 1/30
Ram alone can complete in 30 days
C is correct.
rate of (S+H) = 1/15 ---- (ii)
rate of (H+R) = 1/20 -----(iii)
rate of (R+S+H) = 1/10 ----(iv)
rate of R = 1/10 - 1/15 = 1/30
Ram alone can complete in 30 days
C is correct.
madgmat2019
Joined: 01 Mar 2019
Last visit: 17 Sep 2021
Posts: 584
Location: India
Concentration: Strategy, Social Entrepreneurship
GMAT 1: 580 Q48 V21
GPA: 4
Products:
GMAT 1: 580 Q48 V21
Posts: 584
R+S=1/12........1
S+H=1/15........2
H+R=1/20........3
from 1-2+3....we get R can do the work in 30 days
OA:C
S+H=1/15........2
H+R=1/20........3
from 1-2+3....we get R can do the work in 30 days
OA:C
Ram = R, Shyam = S, Hari =H
Rate of R + S = 1/12,
Rate of S + H = 1/15
Rate of H + R = 1/12
__________________________
2R + 2S + 2H = 1/12 + 1/15 + 1/20
= 5 +4 + 3/60
= 12/60
= 1/5
R + S + H =1/10
R = (R + S + H)- (S +H) = 1/10 -1/15 =6 – 4/60
= 2/60
=1/30
The number of days required by R to complete the work = 30 days(C)
Rate of R + S = 1/12,
Rate of S + H = 1/15
Rate of H + R = 1/12
__________________________
2R + 2S + 2H = 1/12 + 1/15 + 1/20
= 5 +4 + 3/60
= 12/60
= 1/5
R + S + H =1/10
R = (R + S + H)- (S +H) = 1/10 -1/15 =6 – 4/60
= 2/60
=1/30
The number of days required by R to complete the work = 30 days(C)
Archit3110
Major Poster
Joined: 18 Aug 2017
Last visit: 09 Sep 2026
Posts: 8,815
Status:You learn more from failure than from success.
Location: India
Concentration: Sustainability, Marketing
GMAT Focus 1: 545 Q79 V79 DI73
GMAT Focus 2: 645 Q83 V82 DI81
GPA: 4
WE:Marketing (Energy)
GMAT Focus 2: 645 Q83 V82 DI81
Posts: 8,815
Total work
1/12+1/15+1/20= 12/60;1/5
Rams work;
1/10-1/15= 1/30
30 days IMO C
A piece of work can be done by Ram and Shyam in 12 days, by Shyam and Hari in 15 days and by Hari and Ram in 20 days. Ram alone will complete the work in how many days?
A. 35
B. 32
C. 30
D. 28
E. 25
Posted from my mobile device
1/12+1/15+1/20= 12/60;1/5
Rams work;
1/10-1/15= 1/30
30 days IMO C
A piece of work can be done by Ram and Shyam in 12 days, by Shyam and Hari in 15 days and by Hari and Ram in 20 days. Ram alone will complete the work in how many days?
A. 35
B. 32
C. 30
D. 28
E. 25
Posted from my mobile device
Given that A piece of work can be done by Ram and Shyam in 12 days, by Shyam and Hari in 15 days and by Hari and Ram in 20 days. And we need to find Ram alone will complete the work in how many days?
Let Rate of Ram be R, Shyam be S and Hari be H.
We will be using Rate * Time = Work done formula.
Since work done is same so we will take work done as 1
A piece of work can be done by Ram and Shyam in 12 days
=> Combined Rate = R + S
=> (R+ S) * 12 = 1
=> R + S = \(\frac{1}{12}\) ...(1)
A piece of work can be done by Shyam and Hari in 15 days
=> Combined Rate = S + H
=> (S+ H) * 15 = 1
=> S + H = \(\frac{1}{15}\) ...(2)
A piece of work can be done by Hari and Ram in 20 days
=> Combined Rate = H + R
=> (H+ R) * 20 = 1
=> H + R = \(\frac{1}{20}\) ...(3)
(1) - (2) we get
R + S - (S + H) = \(\frac{1}{12}\) - \(\frac{1}{15}\)
=> R - H = \(\frac{5}{60}\) - \(\frac{4}{60}\) = \(\frac{1}{60}\) ...(4)
(3) + (4) we get
H + R + R - H = \(\frac{1}{20}\) + \(\frac{1}{60}\) = \(\frac{3}{60}\) + \(\frac{1}{60}\) = \(\frac{4}{60}\) = \(\frac{1}{15}\)
=> 2R = \(\frac{1}{15}\)
=> R = \(\frac{1}{30}\)
Ram alone will complete the work in how many days
=> R * Time = 1
=> \(\frac{1}{30}\) * Time = 1
=> Time = 30 days
So, Answer will be C
Hope it helps!
Watch the following video to learn How to Solve Work Rate Problems
_________________
Let Rate of Ram be R, Shyam be S and Hari be H.
We will be using Rate * Time = Work done formula.
Since work done is same so we will take work done as 1
A piece of work can be done by Ram and Shyam in 12 days
=> Combined Rate = R + S
=> (R+ S) * 12 = 1
=> R + S = \(\frac{1}{12}\) ...(1)
A piece of work can be done by Shyam and Hari in 15 days
=> Combined Rate = S + H
=> (S+ H) * 15 = 1
=> S + H = \(\frac{1}{15}\) ...(2)
A piece of work can be done by Hari and Ram in 20 days
=> Combined Rate = H + R
=> (H+ R) * 20 = 1
=> H + R = \(\frac{1}{20}\) ...(3)
(1) - (2) we get
R + S - (S + H) = \(\frac{1}{12}\) - \(\frac{1}{15}\)
=> R - H = \(\frac{5}{60}\) - \(\frac{4}{60}\) = \(\frac{1}{60}\) ...(4)
(3) + (4) we get
H + R + R - H = \(\frac{1}{20}\) + \(\frac{1}{60}\) = \(\frac{3}{60}\) + \(\frac{1}{60}\) = \(\frac{4}{60}\) = \(\frac{1}{15}\)
=> 2R = \(\frac{1}{15}\)
=> R = \(\frac{1}{30}\)
Ram alone will complete the work in how many days
=> R * Time = 1
=> \(\frac{1}{30}\) * Time = 1
=> Time = 30 days
So, Answer will be C
Hope it helps!
Watch the following video to learn How to Solve Work Rate Problems
_________________
How to Solve :
All Quant Topics Theory || Last Two Digits of Exponents Ending with 1, 2, 3, 4, 5, 6, 7, 8, 9 || Units' Digit Problems || Even and Odd || Divisibility Rules || Positive and Negative || Absolute Value Basics || Inequalities || Absolute Value + Inequality || Functions and Custom Characters || LCM & GCD || Remainders || Factors and Multiples || Arithmetic and Geometric Progression || Co-ordinate Geometry || Circles || Probability: Coin Toss || Work Rate || Statistics || Stem & Leaf Plot || Box And Whisker Plot
GMAT Club Topic Wise Problems
All Quant Topics Theory || Last Two Digits of Exponents Ending with 1, 2, 3, 4, 5, 6, 7, 8, 9 || Units' Digit Problems || Even and Odd || Divisibility Rules || Positive and Negative || Absolute Value Basics || Inequalities || Absolute Value + Inequality || Functions and Custom Characters || LCM & GCD || Remainders || Factors and Multiples || Arithmetic and Geometric Progression || Co-ordinate Geometry || Circles || Probability: Coin Toss || Work Rate || Statistics || Stem & Leaf Plot || Box And Whisker Plot
GMAT Club Topic Wise Problems
Posts: 4
LCM (12,15,20)= 60
R+S= 60/12= 5
S+H= 50/15= 4
H+R= 60/20= 3
(R+S)- (S+H)+ (H+R)= 5-4+3
2R= 4
R=2
Time taken by R= 60/2= 30
is this the correct approach?
R+S= 60/12= 5
S+H= 50/15= 4
H+R= 60/20= 3
(R+S)- (S+H)+ (H+R)= 5-4+3
2R= 4
R=2
Time taken by R= 60/2= 30
is this the correct approach?
Moderator:
Announcements
Tuck at Dartmouth
AI at Dartmouth Tuck: How the School Is Preparing Leaders for the Age of Artificial Intelligence
Inside the courses, research, and hands-on learning defining wise, decisive leadership in an AI-driven world.
Read More
Inside the courses, research, and hands-on learning defining wise, decisive leadership in an AI-driven world.
Read More
Top 5 GMAT Debrief Videos
Success stories and strategies from high-scoring candidates.