Help with Buoyant forces

[ramin86]

(a) A light balloon is filled with 371 m3 of helium. At 0°C, the balloon can lift a payload of what mass?

(b) In Table 14.1, observe that the density of hydrogen is nearly half the density of helium. What load can the balloon lift if filled with hydrogen?

I really have no clue where to start for these problems. You're given the volume and that the denisty of helium is 1.79E-1, but I don't get how to find the payload.

[Doc Al]

Both problems require understanding of Archimede's principle: The buoyant force on an object imersed in a fluid equals the weight of the displaced fluid. In these problems, the balloons displace air. So start by figuring out the buoyant force acting (upward) on each balloon.