Hello

I believe the answer to part a. of this question is 4 ballons. Part b. is beyond the scope of my abilities. Any help would be appreciated.

a. If one Helium (gas) tank can fill 16 nine inch (diameter) spherical balloons, then the same tank can fill how many 3 feet (diameter) balloons?

b. How many small marbles of radius r can be filled in a large cylindrical tumbler of height H and radius R ?

Thanks,

KP