Verified Answer :

The leaning tower of pisa is cylindrical and as such the volume can be approximated using the same formula as a regular cylinder.

Volume of a cylinder (V) = \(\pi r^{2}h\)

Assume \(\pi\) = \(\frac{22}{7}\)
    V = 9891 \(m^{3}\)
    h = 56 m 

Let: Radius= r
       Diameter= D 
Then D= 2r

By substituting the known values into the equation and transposing one can formulate an equation to solve for D.
V = \(\pi r^{2}h\)
: . 9891\(m^{3}\) = \(\frac{22}{7} * r^{2} * (56m)\)

Making r the subject of this equation:
 \(r^{2} = \frac{V}{( \pi ) (h)}\)
 \(r = \sqrt{ \frac{V}{ ( \pi ) (h)} }\)

Since the Diameter is 2r then multiply both sides of the equation by 2
: . \(2r = 2 (\sqrt{ \frac{V}{( \pi ) (h)} } )\)
thus     D =  \(2 (\sqrt{ \frac{V}{( \pi ) (h)} } )\)

Part B:

Since the formula for Diameter has be formulated, substitute the values of the variables and solve for D
    D = \(2( \sqrt{ \frac{9891 m^{3} }{ (\frac{22}{7}) (56m) }\)
: . D = \(2( \sqrt{56.199 m^{2} })\)
        = 2 * 7.497m
        =  14.993 m  

Part C:
Therefore it can be concluded that the Diameter of the base of the Leaning Tower of Pisa is approximately 14.99 meters.