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A person finishes a certain work for 2 hours, another person finishes the same work for 4 hours. How much time will it take for the two to finish the work? (please explain how you solved this)

Lunar  Apr 22, 2016
 #1
avatar+88898 
+5

Notice that the first person  does 1/2 the job in one hour and the second does 1/4 of the job in one hour.....so......together.......they complete  1/2 + 1/4  = 2/4 + 1/4  = 3/4 of the job in one hour

 

Now.....all you have to do is to invert this fraction, and it will give you the time that it will take both of them working together to complete the job   =   4/3 hrs.   = 1 + 1/3 hrs   = 1 hr, 20 min

 

This makes sense....if you can complete 1/2 of a job in one hour.....it will take you the reciprocal of this fraction, time wise, to compllete the whole job = 2/1 hrs  = 2 hrs

 

 

cool cool cool

CPhill  Apr 22, 2016
 #2
avatar+65 
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Thanks alot CPhill! :)

Lunar  Apr 22, 2016
 #3
avatar+88898 
0

No prob......

 

 

cool cool cool

CPhill  Apr 22, 2016

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