The net weight of the balloon must be zero.
The forces acting on the hot-air balloon when it hovers at a fixed altitude are gravitational force and the upthrust of the hot air. As the balloon is at a fixed altitude, the two forces balance each other resulting in zero net force. Thus, the weight of the balloon is balanced by the upthrust, so the balloon is weightless at this time of the flight.
If a bus travels 30 km in 1/2 hr, then in one hr, he can travel twice the distance.
30*2=60 km
Final answer: 60 km per hr
I think the distance that should be used is the distance that one expects to be from the game you are hunting. Before taking a shotgun for a gobbler or even for ducks or other animals, you need to see how your gun performs by patterning it at various ranges with the load you want to use.