Source: Veritas Prep
Working at their respective constant rates, Paul, Abdul, and Adam alone can finish a certain work in 3, 4, and 5 hours respectively. If all three work together to finish the work, what fraction of the work will be done by Adam?
A. 1/4
B. 12/47
C. 1/3
D. 5/12
E. 20/47
The OA is B
Working at their respective constant rates, Paul, Abdul and
This topic has expert replies
-
- Moderator
- Posts: 2209
- Joined: Sun Oct 15, 2017 1:50 pm
- Followed by:6 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
GMAT/MBA Expert
- Jay@ManhattanReview
- GMAT Instructor
- Posts: 3008
- Joined: Mon Aug 22, 2016 6:19 am
- Location: Grand Central / New York
- Thanked: 470 times
- Followed by:34 members
Work done by Paul, Abdul, and Adam alone in one hour = 1/3, 1/4 and 1/5, respectively.BTGmoderatorLU wrote:Source: Veritas Prep
Working at their respective constant rates, Paul, Abdul, and Adam alone can finish a certain work in 3, 4, and 5 hours respectively. If all three work together to finish the work, what fraction of the work will be done by Adam?
A. 1/4
B. 12/47
C. 1/3
D. 5/12
E. 20/47
The OA is B
Work done by Paul, Abdul, and Adam together in one hour = 1/3 + 1/4 + 1/5 = 47/60
Fraction of the work will be done by Adam = Part of the work done by Adam / Part of the work done by Adam Paul, Abdul, and Adam together = (1/5) / (47/60) = 12/47
The correct answer: B
Hope this helps!
-Jay
_________________
Manhattan Review GMAT Prep
Locations: GMAT Classes Glasgow | GMAT Prep Courses Hyderabad | LSAT Prep Courses San Diego | Manhattan Prep Classes SAT | and many more...
Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7247
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
BTGmoderatorLU wrote:Source: Veritas Prep
Working at their respective constant rates, Paul, Abdul, and Adam alone can finish a certain work in 3, 4, and 5 hours respectively. If all three work together to finish the work, what fraction of the work will be done by Adam?
A. 1/4
B. 12/47
C. 1/3
D. 5/12
E. 20/47
The OA is B
We can let t = the time during which all three people work together; thus, the combined work is:
(1/3)t + (1/4)t + (1/5)t = (20/60)t + (15/60)t + (12/60)t = (47/60)t
Thus, Adam completed (1/5)t/[(47/60)t] = 60/(47 x 5) = 12/47 of the job.
Answer: B
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7247
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
We can let t = the time during which all three people work together; thus, the combined work is:BTGmoderatorLU wrote:Source: Veritas Prep
Working at their respective constant rates, Paul, Abdul, and Adam alone can finish a certain work in 3, 4, and 5 hours respectively. If all three work together to finish the work, what fraction of the work will be done by Adam?
A. 1/4
B. 12/47
C. 1/3
D. 5/12
E. 20/47
The OA is B
(1/3)t + (1/4)t + (1/5)t = (20/60)t + (15/60)t + (12/60)t = (47/60)t
Thus, Adam will complete (1/5)t/(47/60)t = 60/(47 x 5) = 12/47 of the job.
Alternate Solution:
First, let's find how much time it takes for the three of them to complete the job. Notice that in 1 hour, Paul, Abdul and Adam can do 1/3, 1/4 and 1/5 of the job, respectively. Thus, with all of them working together,
1/3 + 1/4 + 1/5 = 47/60
of the job gets done in one hour. If 47/60 of the job takes one hour to complete, then the whole job will take 60/47 hours to complete.
Next, we can set up a proportion to determine how much of the job gets done by Adam. Keeping in mind that Adam can do 1/5 of the job in one hour, we set up the proportion: "1/5 of the job is to 1 hour as x of the job is to 60/47 hours"
(1/5)/1 = x/(60/47)
x = (1/5)*(60/47) = 12/47
Answer: B
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews