Working alone, Jenny can mop a warehouse in 10 hours. One day her friend Carlos helps her and it only took 5.24 hours. How long would it take Carlos to do it alone?

Answer 1

Lets assume their warehouse is 100 ft² (Could be any any size!)

Then it takes Jen 1 hours to do 10 ft²

So, for both 10 ft²/hr (Jen) x 5.24 hours + C ft²/hour x 5.24 hours = 100 ft2

Solving for Carlos' effort, we get C = 9.084 ft^2/hour

So, if he had to do the whole warehouse (100 ft²), his time would be 100/9,084 = 11 hours