Given that,
The diameter of a tennis ball, d = 2.7 inches
Radius, r = 1.35 inches
The dimensions of the storage shed is 14 feet wide, 15 feet long, and 10 feet high.
Volume of the shed is, V = lbh

We can convert radius from inches to feet :
1 foot = 12 inches
Radius, r = 0.1125 feet
Let there are x number of tennis balls that can fit in the shed. So,

x = 352105.75 balls
or
x = 352106 balls
Hence, 352106 balls can fit in the storage shed.