BRAINLIEST +16 points (Plz respond before 11:59 and an explanation would be very appreciated)

7:

For a cylindrical grain silo, the dimensions are shown in the picture
provided. The weight in pounds, W, of the grain silage inside is generally given by..
W = 3300(40 - d), where d is the distance in feet from the top of the grain to the
top of the silo.
a.

-Use the distributive property to simplify the equation.

-Suppose d = 15 feet. What is the weight of the grain silo?

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

correct answer:

a + bi

it’s the first one your welcome