Answer:
less than
Step-by-step explanation:
If
is the amount of strontium-90 present in the area in year
, and it decays at a rate of 2.5% per year, then

Let
be the starting amount immediately after the nuclear reactor explodes. Then

or simply

So that after 50 years, the amount of strontium-90 that remains is approximately

or about 28% of the original amount.
We can confirm this another way; recall the exponential decay formula,

where
is measured in years. We're told that 2.5% of the starting amount
decays after 1 year, so that

Then after 50 years, we have

since the diameter of the base of the cylinder is 6 feet, then its radius is half that, or 3 feet.
![\bf \textit{volume of a cylinder}\\\\ V=\pi r^2 h~~ \begin{cases} r=radius\\ h=height\\[-0.5em] \hrulefill\\ r=3\\ h=9 \end{cases}\implies V=\pi (3)^2(9)\implies V=81\pi](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Bvolume%20of%20a%20cylinder%7D%5C%5C%5C%5C%0AV%3D%5Cpi%20r%5E2%20h~~%0A%5Cbegin%7Bcases%7D%0Ar%3Dradius%5C%5C%0Ah%3Dheight%5C%5C%5B-0.5em%5D%0A%5Chrulefill%5C%5C%0Ar%3D3%5C%5C%0Ah%3D9%0A%5Cend%7Bcases%7D%5Cimplies%20V%3D%5Cpi%20%283%29%5E2%289%29%5Cimplies%20V%3D81%5Cpi)
You just have to divide the 1/2 a pound by 8, or equivalently multiply by (1/8):
(1/2)*(1/8) = 1/16 of a pound
Answer:
<h2>z = 15</h2>
Step-by-step explanation:

<u>Cross multiply </u>
That's

<u>Send 15 to the right side of the equation</u>

Divide both sides by 15

We have the final answer as
<h3>z = 15</h3>
Hope this helps you