A box of cereal measures 19.5 cm by 30 cm by 6.5 cm. It is filled to 80% capacity. A cereal bowl is hemispherical and measures 12 cm wide. How many bowls of cereal can be filled by one box of cereal?

The answer to this question is 6.

Volume of cereal box=19.5*30*6.5=3802.5cc. The volume of cereal is 80% of this=0.8*3802.5=3042cc.

Volume of the cereal bowl is 2/3 (pi) r^3 (half the volume of a sphere 4/3 (pi) r^3) where r=radius=12/2=6cm. The volume is therefore 2/3 (pi) * 216=144 (pi) cc.

The number of full cereal bowls is 3042/144 (pi) = 21.125 / (pi) = 6.72. So 6 cereal bowls can be filled from the cereal in one cereal box.