If a cone has a height that equals twice the diameter of its base, what is its volume in terms of the height

The volume of the cone can be calculated as follows:
volume of cone = (1/3) x pi x (radius)^2 x height > equation 1

We know that the height is twice the diameter, therefore:
h = 2d > equation 2

we also know know that the radius is half the diameter:
r = (1/2) d
d = 2r > equation 3

Substitute with equation 3 in equation 2, we get:
h = 2d = 2 (2r)
h = 4r
 r = (1/4) h> equation 4

Substitute with equation 4 in equation 1, we get:
volume of cone = (1/3) x pi x (radius)^2 x height
                         = (1/3) x pi x (0.25 h)^2 x h
                         = (1/3) x pi x (1/16) h^2 x h
                         = (1/48) x pi x h^3

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.