Three computers can print out a task in 10 min, 15 min, and 30 min, respectively. How long would it take to complete the task with all three computers working?

Question

Three computers can print out a task in 10 min, 15 min, and 30 min, respectively. How long would it take to complete the task with all three computers working?
  

Answer 1

the classic work problem (W = rt).  You need to find the rate of each computer.  We do this by finding the reciprocal of the times.  Once you do this you can find the time by solving w=rt.  W is equal to one, because you are only doing one task.

 

w =(1/10 + 1/15 + 1/30)t    >>>>  1 = 6/30(t)   >>>>>   1 = 1/5(t) >>>>> 5=t

 

 

it takes 5 minutes with all three working together.