Answer:
3 or 2.999 (probably 3)
Step-by-step explanation:
So the volume of a cylinder = πr^2 * h
h = height
r = radius
now we know the radius. Leaving us with a simple equation which is:
π*9*h = 9π*h = 84.78 =
π*h = 9.42
h = 9.42 / π = 2.99847912785......
but we can round this to 2.999 or just 3. if you use 2.999 the volume is 84.79 which is as close as I'm gonna try to get. And you might ask why we're rounding to 2.999 and not 2.998? This is because that huge number is the minimum. And 2.998 is smaller than that huge number, meaning it would technically be less than 84.78 cubic ft. But this doesn't really matter because the answer your teacher is probably looking for is 3.
Reference my work if you're are confused, however, it's really messy so sorry about that.