Answer:
we know that
volume of a grain silo=volume of a cylinder+volume of a hemisphere
volume of a grain silo=17000 ft³
volume of a cylinder=pi*r²*h
h=30 ft
volume of a cylinder=pi*r²*30----> 30*pi*r² ft³
volume of a hemisphere=(2/3)*pi*r³
so
17000=30*pi*r²+(2/3)*pi*r³-----> multiply by 3---> 51000=282.60*r²+6.28*r³
6.28*r³+282.60*r²-51000=0
using a graph tool
see the attached figure
the solution is
r=11.942 ft-------> r=11.9 ft
the answer is
The radius of the silo is 11.9 ft
