Answer:
5^2 = 100
100 x 3.14 = 314
Now we multiply by 20 since it's the height.
314 x 20 = 6,280 cm^3 is your answer.
Formula of cylinder:
H x πr^2
Height x pi(3.14 or 22/7 depending what they tell you to use for pi) x radius being squared (your radius is half of your diameter or given radius).