Let's make this simple. Let's have the small cone have a radius 1 and the height 1. This would make the bigger
cone
have a radius of 1 and the height of 2.
With this information, lets get the volume of both cones. The formula is this:

Plug in numbers:
Small cone:

Big cone:

The small cone has a volume of

The big cone has a volume of

Now, you want to find how many small cones you need to have the same total volume of the big cone.

You have the difference of pi over 3 comparing the big cone to the small one. You realize that the small cone has the same volume of that. Therefore,
you need 2 small cones to have the same total volume as the larger cone
N = number of compounding periods
Years = log (total / principal) / n * log (1 + rate / n)
Years = log (750 / 500) / 4 * log (1 + .025/n)
Years = log (1.5) / 4 * log (1<span><span>.00625)
</span>
</span> <span>Years = 0.17609125906 / 4 * 0.0027058933759
</span><span>Years = 0.17609125906
</span>
/
<span>
<span>
<span>
0.0108235735
</span>
</span>
</span>
Years =
<span>
<span>
<span>
16.2692348382
</span>
</span>
</span>
Source Calculator
http://www.1728.org/compint.htm
That the variable Z is directly proportional to X and inversely proportional to Y means Z = A (X/Y)
=> A = Z* Y / X
=> 9.5 * 6 / 3 = Z * 12 /8
=> Z = 9.5 * 8 * 6 / (3 * 12) = 12.67
Answer: 12.67