The correct answer is 5460 cubic feet or 5460 
Explanation:
The silo has a cylindrical shape, in this context, the volume of the silo or any other cylinder can be calculated by using the formula
. In this formula the symbol
refers to the number 3.1415..., the letter
refers to the radius of the base and the letter
refers to the height.
Moreover, in this case, it is known the heigh (21 feet) and the area of the base (260 square feet). Additionally, this area of the base is the result of the formula
, which is exactly the first section of the formula to find the volume. This implies that by multiplying the area of the base by the height the volume is known. Here is the process:
or
(Area of the base × height)
× 

Think about it this way, what is 5x3??? 15 right. Ok then what is 5x30???? 150. So the store should sell each soccer ball for $5 each:)
$616 because 550 times .12(12% as decminal) is 66. $66 plus $550 is $616
Click on the picture! This is the explanation in accident I deleted it hope it helps!