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Mr. Ito's assistant takes twice as long to complete a computer task as Mr. Ito. If takes both experts 6 hours to complete the task, how long will it take each of them to do the job alone?

 Jul 20, 2020
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Ito time  = i                              Ito RATE =   1 task / i    = 1/i

A = assistant time  =  2i          A*s't RATE                   = 1/2i

 

One task is completed by both working in 6 hours

    1 task / (1/i  + 1/2i)   = 6

1/(1/i + 1/2i) = 6     solve for  i

1 / ( 3/(2i) ) = 6

3/(2i)  = 1/6

2 i = 18

i = 9  hr        A*s't = 18  hr

 

 

 

This whole method reduces to this:

 

1/i  + 1/2i = 1/6

3/2i = 1/6

2i = 18

i = 9

 Jul 20, 2020

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