A9. A 200-liter cistern for apple juice has the shape of a truncated cylinder and is $1 \mathrm{~m}$ high. How many liters of juice are in the cistern if it is filled to a height of $15 \mathrm{~cm}$?
(A) 10
(B) 15
(C) 20
(D) 25
(E) 30
A9 If the cistern is $100 \mathrm{~cm}$ high, each cm of height corresponds to $200 l: 100=2 l$ of water. If the cistern is filled to a height of $15 \mathrm{~cm}$, it contains $15 \cdot 2 l=30 l$ of water.