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Originally posted by david01 on 30 Dec 2009, 01:46.
Last edited by david01 on 08 Mar 2010, 02:55, edited 1 time in total.
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If ‘A’ can complete a task in 3 hours and ‘B’ can complete the same task in 6 hours, how long will it take if both of them work together to complete the task?
Please explain the logic.
Thanks
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first thing david the problem never asked about the mean time , the problem is asking how much time it will if bth does the work together . there is a huge diff in bth the cases.
secondly there is a direct formula to handle such problem
if A takes x hrs and B takes y hrs to do a work independently then , combining they will take x*y/(x+y) hrs
The best approach to these problems is to get the 1 hr work done by each participant.
To explain: If ‘A’ can complete a task in 3 hours and ‘B’ can complete the same task in 6 hours, how long will it take if both of them work together to complete the task?
In 3 hrs, A can do = 1 Task (read as complete Task) In 1 hr, A can do \(=\frac{1}{3}\) Task
Similarly In 6 hrs, B can do = 1 Task In 1 hr, B can do \(=\frac{1}{6}\) Task
Therefore the task done by both A and B in 1 hr \(=\frac{1}{3} + \frac{1}{6} = \frac{1}{2}\) Task
Now \(\frac{1}{2}\) Task is done by both A & B in = 1 hr 1 Task (read as complete Task) is done by both A & B in \(= 1 / \frac{1}{2}\) hrs = 2 hrs
Reason for this detail approach is that with this understanding you can solve questions involving more than 2 people and also with complex combinations....
Hope this helps!
Cheers! JT
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.