Answer: 25% of the ice cream must be eaten to insure it does not overflow the cone when it melts.
Explanation:
1. You must calculate the area of spherical scoop of ice cream with the following formula for calculate the volume of a sphere:

Where
is the radius (
)

2. Now, you need to calculate the volume of the sugar cone with the following formula:

Where
is the radius (
) and
is the height (
):

3. When the ice cream melt, the percent of the cone that will be filled is:
%
4. Therefore, the percent of the ice cream that must be eaten to insure it does not overflow the cone when it melts, is:
%
%
%