Depends whether Sue shows up to distract Sam and Brian.
Add more if Jane is wearing a 2 piece swimming suit.
Even more if its a cut off: Ratio of time to clothes is inversely proportional to the wetness of the clothes.
You got it.
Even if you play the stated problem straight, you can't reach a conclusion with the factors given.
It will depend on the method they use to wash the car. For example, when I used to wash my car, I had a system that would reduce the overall time and effort - I'd use the hose in one hand and a sponge in the other. No soap.
If both boys used this method, they'd need two hoses, and the hoses would need to be from two different houses, because if they both were using water from the same house, the flow would be reduced to each hose, increasing their rate of washing.