Question

Each valves A, B, and C, when open, releases water into a tank at its own constant rate. With all three valves open, the tank fills in 1 hour, with only valves A and C open it takes 2 hours, and with only valves B and C open it takes 3 hours. How long will it take to fill the tank with only valves A and B open?

Answer 1

This is the one I said something before, except I'm not positive it's right.

Answer 2

It's going to be a reciprocal of reciprocals I think. Maybe you want someone who can answer in two seconds ..

Answer 3

I figure it this way. Suppose the flow rate of a plus that of b plus that of c is just enough to fill the tank in one hour (some number of gallons per hr).

Answer 4

then what?