Please help me on this

Aball is dropped from a height of 10m above the ground. it bounce to 90% of its previous height on each bounce. what is the approximate height that the ball bounce to the fourth bounce?

Hannah paid $3.20 for 16 ounces of potato chips. hank paid $3.23 for 17 ounces of potato chips. who paid less per ounces?

The volume of a box varies directly with its length if a box in the group has a length of 30inches and k=24 what is its volume