Respuesta :
Let
x---------> the cylinder's height
y--------> the cylinder's diameter
we know that
x=2*y
[volume of the tank]=[volume of the cylinder]+[volume of two hemispherical ends]
step 1
find the volume of the cylinder
[volume of the cylinder]=pi*r²*h
r=y/2
h=x----> 2*y
so
[volume of the cylinder]=pi*(y/2)²*(2*y)-----> pi*y³/2
step 2
find the volume of two hemispherical ends
but
two hemispherical ends is equals to one sphere
so
[volume of the sphere]=(4/3)*pi*r³
r=y/2
[volume of the sphere]=(4/3)*pi*(y/2)³----> (1/6)*pi*y³
step 3
find the radius of the tank
we know that
1 ft³---------> 7.48 gal
X ft³-------> 1000 gal
X=1000/7.48--------> X=133.69 ft³
[volume of the tank]=[volume of the cylinder]+[volume of two hemispherical ends]
so
133.69=[pi*y³/2]+[(1/6)*pi*y³]-----> 133.69=y³*[(pi/2)+(pi/6)]
133.69=y³*[(2/3)*pi]-----> y³=133.69/[(2/3)*pi]-----> y³=63.83
y=∛63.83---------> y=4 ft
therefore
the radius is y/2-------> r=4/2-----> r=2 ft
the answer is
r=2 ft
x---------> the cylinder's height
y--------> the cylinder's diameter
we know that
x=2*y
[volume of the tank]=[volume of the cylinder]+[volume of two hemispherical ends]
step 1
find the volume of the cylinder
[volume of the cylinder]=pi*r²*h
r=y/2
h=x----> 2*y
so
[volume of the cylinder]=pi*(y/2)²*(2*y)-----> pi*y³/2
step 2
find the volume of two hemispherical ends
but
two hemispherical ends is equals to one sphere
so
[volume of the sphere]=(4/3)*pi*r³
r=y/2
[volume of the sphere]=(4/3)*pi*(y/2)³----> (1/6)*pi*y³
step 3
find the radius of the tank
we know that
1 ft³---------> 7.48 gal
X ft³-------> 1000 gal
X=1000/7.48--------> X=133.69 ft³
[volume of the tank]=[volume of the cylinder]+[volume of two hemispherical ends]
so
133.69=[pi*y³/2]+[(1/6)*pi*y³]-----> 133.69=y³*[(pi/2)+(pi/6)]
133.69=y³*[(2/3)*pi]-----> y³=133.69/[(2/3)*pi]-----> y³=63.83
y=∛63.83---------> y=4 ft
therefore
the radius is y/2-------> r=4/2-----> r=2 ft
the answer is
r=2 ft