Answer:
11.28 ft
Step-by-step explanation:
The volume of a cylinder can be written as;
Volume V1 = πr^2 h
The volume of an hemisphere can be written as;
Volume V2 = (2/3)πr^3
The total volume of the silo is;
V = V1 + V2
V = πr^2 h + (2/3)πr^3
Given;
Volume of silo V= 15000 ft^3
Height of cylinder part h = 30 ft
Substituting the values;
V = πr^2 h + (2/3)πr^3
15000 = 30πr^2 + (2/3)πr^3
15000/π = 30r^2 + (2/3)r^3
2r^3 + 90r^2 - (15000×3/π) = 0
Solving the equation, we have;
r = 11.28 ft or -15.61 ft or -40.67 ft
Since the radius cannot be negative;
Radius r = 11.28 ft
