Part A.
To determine the volume of the barrel we use the formula for the volume of a cylinder:

where r is the radius of the base of the cylinder and h is its height.
For the barrel:

Substituting the above values in the formula, we get:

Answer part A:

Part B.
Recall that:

Answer part B: There are 231 cubic inches in 1 gallon.
Part C.
Diagram:
The barrel can contain 57 gallons of water, if it is at 2/3 of its capacity then there are

of water inside the barrel.
Answer part C:
