ANSWER

Step-by-step explanation
To find how much chocolate Michelle needs, we have to find the volume of the cone-shaped tree.
The volume of a cone is:

where r = radius; h = height
The diameter is 2 times the radius, which means that the radius of the base of the cone is half the diameter. That is:

Therefore, the volume of the cone-shaped tree is:

That is the amount of chocolate that Michelle needs.