|
|
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.
28 Jul 2021, 23:16
Kudos
Bookmarks
A
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:
81% (02:24) correct
19%
(02:53)
wrong
based on 159
sessions
History
Date
Time
Result
Not Attempted Yet
A and B can do a piece of work in 40 days, B and C can do it in 120 days. If B alone can do it in 180 days, in how many days will A and C do it together?
A. 45 days
B. 22.5 days
C. 25 days
D. 18 days
E. 12 days
A. 45 days
B. 22.5 days
C. 25 days
D. 18 days
E. 12 days
29 Jul 2021, 00:33
Kudos
Bookmarks
rajatchopra1994
No need to solve this numerically. If A and B together do a piece of work in 40 days, then either of A or B will take more than 40 days to do it alone. Similarly, we can see that either of B and C will take more than 120 days to do the work alone.
This means that A and C will also take more than 40 days to do it together.
The only answer that matches this is (A).
General Discussion
15 Nov 2021, 10:44
Kudos
Bookmarks
That is how I solved it...
Since we have that B can do the work in 180 days, let's say W= 180 and B(rate) = 1
W = R * T
180 = (1) * 180
A+B = 40 days
W = R * T
180 = (1+A) * 40
(1+A) = 180/40 = 9/2 (now we have to subtract B=1 :. A=7/2)
B+C = 120 days
W = R * T
180 = (1+C) * 120
(1+C) = 180/20 = 3/2 (now we have to subtract B=1 :. C=1/2)
returning to the equation:
W = R * T
180 = A+C * T
T = 180/(A+C)
T = 180/( 7/2+1/2) = 45
A+C can make it in 45 days
Since we have that B can do the work in 180 days, let's say W= 180 and B(rate) = 1
W = R * T
180 = (1) * 180
A+B = 40 days
W = R * T
180 = (1+A) * 40
(1+A) = 180/40 = 9/2 (now we have to subtract B=1 :. A=7/2)
B+C = 120 days
W = R * T
180 = (1+C) * 120
(1+C) = 180/20 = 3/2 (now we have to subtract B=1 :. C=1/2)
returning to the equation:
W = R * T
180 = A+C * T
T = 180/(A+C)
T = 180/( 7/2+1/2) = 45
A+C can make it in 45 days
