If r = 7 units and x = 8 units, then what is the volume of the cylinder shown above?
A.
210 cubic units
B.
56 cubic units
C.
1,568 cubic units
D.
392 cubic units
Strange as it may seem, NONE of the choices on the list is the volume of that cylinder,
The volume of any cylinder is (π) (radius)² (height).
We know all of these numbers. We only need to pour them into the hopper on top of the volume machine, and turn the crank.
(π) x (radius)² x (height)
= (3.14...) x (7 units)² x (8 units)
= (3.14...) x (49 units² x 8 units)
= (3.14...) x (392 units³) = 1,231.5... units³
I don't see that number among the choices, or anything close to it.
Choice-D is interesting. As we saw during our calculation, 392 is (radius)² x (height). But that's not the volume, because it hasn't been multiplied by π yet.
