SOLUTION: If the total volume of the silo (including the part inside the roof section) is 18000 ft3 and the cylindrical part is 50 ft tall, what is the radius of the silo? Volume of a Cyli

Algebra ->  Volume -> SOLUTION: If the total volume of the silo (including the part inside the roof section) is 18000 ft3 and the cylindrical part is 50 ft tall, what is the radius of the silo? Volume of a Cyli      Log On


   

Question 871926: If the total volume of the silo (including the part inside the roof section) is 18000 ft3 and the cylindrical part is 50 ft tall, what is the radius of the silo?
Volume of a Cylinder =πr^2h
Volume of a Sphere =(4/3)πr^3
Alright, this is my third time posting this question and I won't bother you again, however you keep telling me that I'm solving for the wrong thing, however this is EXACTLY how the question is worded in my homework. I can't solve for a cone shape because my teacher has decided that this silo has a hemisphere shape. So I MUST solve for a spherical shape.
Answer by josgarithmetic(39626) About Me  (Show Source):
You can put this solution on YOUR website!
Okay, understood.

The roof section is probably meant as the half spheric part.
h%2Api%2Ar%5E2%2B%281%2F2%29%284%2F3%29pi%2Ar%5E3=v and your v is 18000 cubic feet.

...
h%2Api%2Ar%5E2%2B%282%2F3%29pi%2Ar%5E3-18000=0
50%2Api%2Ar%5E2%2B%282%2F3%29pi%2Ar%5E3-18000=0
%282%2F3%29pi%2Ar%5E3%2B50%2Api%2Ar%5E2-18000=0
highlight_green%282%2Api%2Ar%5E3%2B150%2Api%2Ar%5E2-54000=0%29
highlight_green%28pi%2Ar%5E3%2B75%2Api%2Ar%5E2-27000=0%29.
You are looking for the roots or zeros, so there should be one real value that should make sense. This is a cubic equation, and maybe a graphing tool would be useful.