Answer:
64:1
Explanation:
For similar lengths, we use the relationship
where A and B are the measurements of the two figures' lengths and k is the scale factor.
For similar volumes, we use the relationship
where A and B are the measurements of the two figures' volumes and k is the scale factor.
Since lengths are given, we use the first formula to find k:

The 2nd formula also tells us that volumes are
of each other. So

That means the larger cone has a volume that is 64 times the smaller. So the ratio is 64:1