SOLUTION: One robot can vacuum a house in 10 hours. If a second robot is added and both are used, the same job can be completed in 3 hours. How long would it take the second robot alone to d

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Question 613378: One robot can vacuum a house in 10 hours. If a second robot is added and both are used, the same job can be completed in 3 hours. How long would it take the second robot alone to do the same job?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi, 

One robot can vacuum a house in 10 hours. If a second robot is added and both

 are used, the same job can be completed in 3 hours

Let x represent the time the second robot would take alone:

PER hour KEY:

 1/10 + 1/x = 1/3 ||Multiplying thru by 30x so as all denominators = 1

 3x + 30 = 10x

     30 = 7x

     4 2/7 hr = x, the time the second robot would take alone