February 21, 2019 February 21, 2019 10:00 PM PST 11:00 PM PST Kick off your 2019 GMAT prep with a free 7day boot camp that includes free online lessons, webinars, and a full GMAT course access. Limited for the first 99 registrants! Feb. 21st until the 27th. February 23, 2019 February 23, 2019 07:00 AM PST 09:00 AM PST Learn reading strategies that can help even nonvoracious reader to master GMAT RC. Saturday, February 23rd at 7 AM PT
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 53061

A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
30 Jan 2019, 01:19
Question Stats:
40% (01:52) correct 60% (01:50) wrong based on 40 sessions
HideShow timer Statistics



Director
Joined: 18 Jul 2018
Posts: 675
Location: India
Concentration: Finance, Marketing
WE: Engineering (Energy and Utilities)

Re: A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
30 Jan 2019, 01:28
Total work to be done = LCM(6,8,12) = 24 units A can do 4 units per day B can do 3 units per day C can do 2 units per day B+C in 1 day = 5 units for 2 days, 10 units will be completed by B and C. Remaining is 14 units. Now A and B work together, They can do 4+3 = 7 units per day. Then 14 units will be completed in 2 days. A is the answer.
_________________
Press +1 Kudo If my post helps!



VP
Joined: 31 Oct 2013
Posts: 1157
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)

Re: A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
30 Jan 2019, 01:54
Bunuel wrote: A, B and C can do a work in 6, 8, 12 days respectively. B and C work together for 2 days and then A takes C's place. How long will it take to finish the work?
A. 2 days B. 3 days C. 4 days D. 5 days E. 6 days LCM method is suitable here.
LCM of 6,8,12 =24 units of work.
A's work = 4 units /day B's work = 3 units/days C's work = 2 units/day
(A + C)' 2 days work = 3 +2 = 5 *2 = 10 units.
Remaining Work = 24  10 = 14
14 Units done by (A + B)
(A + B)'s performance in a day = 4 + 3 =7
14/7 = 2 days.
Thus, A and B will take only 2 days to finish the remaining work .
A is the correct answer.



SVP
Joined: 18 Aug 2017
Posts: 1887
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)

A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
30 Jan 2019, 02:00
Bunuel wrote: A, B and C can do a work in 6, 8, 12 days respectively. B and C work together for 2 days and then A takes C's place. How long will it take to finish the work?
A. 2 days B. 3 days C. 4 days D. 5 days E. 6 days rate of B & C = 1/8 + 1/12 ; 5/24 so amount of work done by b & c = 5/24 * 2 = 5/12 work left = 15/12 = 7/12 rate of work of A & B = 1/6+ 1/8 = 7/24 since w=r*t w=7/12 , r = 7/24 t = 24/12 = 2 total work would be finished in 2 days of B& C and 2 days of A & B = 2+2 = 4 IMO C
_________________
If you liked my solution then please give Kudos. Kudos encourage active discussions.



Intern
Joined: 19 Jan 2019
Posts: 7

Re: A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
14 Feb 2019, 08:35
I just have one doubt... Is the question asking the total number of days or just the days in which A&b finish the remaining work. If it was total number of days then the answer is 4 days . If the question is asking only the number of days it took A&b to finish the remaining work then the answer is 2 days ..... Which one is the right one. As far as I understood the question, it's asking about the days A&b finished the work, but OA is C.. Can anyone clear my doubt..
Posted from my mobile device



SVP
Joined: 18 Aug 2017
Posts: 1887
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)

Re: A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
14 Feb 2019, 08:41
thyagi wrote: I just have one doubt... Is the question asking the total number of days or just the days in which A&b finish the remaining work. If it was total number of days then the answer is 4 days . If the question is asking only the number of days it took A&b to finish the remaining work then the answer is 2 days ..... Which one is the right one. As far as I understood the question, it's asking about the days A&b finished the work, but OA is C.. Can anyone clear my doubt..
Posted from my mobile device thyagiquestion has asked How long will it take to finish the work?which means total days..
_________________
If you liked my solution then please give Kudos. Kudos encourage active discussions.



Intern
Joined: 20 Nov 2018
Posts: 10

A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
Show Tags
14 Feb 2019, 10:20
Bunuel wrote: A, B and C can do a work in 6, 8, 12 days respectively. B and C work together for 2 days and then A takes C's place. How long will it take to finish the work?
A. 2 days B. 3 days C. 4 days D. 5 days E. 6 days if given n people finishing a work in k days 1/a + 1/b + 1/c + 1/d + .... + 1/n= 1/k (i.e., 1/k th fraction of work done on each day)
given : 1/a = 1/6 1/b = 1/8 1/c = 1/12 b and c work together for two days each day 1/b+1/c two days 2*(1/b+1/c)a replaces c a and b works for say t days t*(1/a+1/b)the sum all the fractions work done should be one 2*(1/b+1/c) + t*(1/a+1/b) = 12*(1/8 + 1/12) + t*(1/6+1/8) = 1 1/4+1/6+7t/24 = 1 5/12 + 7t/24 = 1 7t/24 = 1 5/12 = 7/12 t = 2 days if the question is asking about the amount of time taken to finish the work after A replaces C Option A  2 days if the question is asking for the total time taken to finish the work 2 + 2 = 4 days Option C  4 days  please leave a kudos




A, B and C can do a work in 6, 8, 12 days respectively. B and C work t
[#permalink]
14 Feb 2019, 10:20






