84 is the median of the numbers
Answer:

Step-by-step explanation:
The pool are is divided into 4 separated shapes: 2 circular sections and 2 isosceles triangles. Basically, to calculate the whole area, we need to find the area of each section. Due to its symmetry, both triangles are equal, and both circular sections are also the same, so it would be enough to calculate 1 circular section and 1 triangle, then multiply it by 2.
<h3>Area of each triangle:</h3>
From the figure, we know that <em>b = 20ft </em>and <em>h = 25ft. </em>So, the area would be:

<h3>Area of each circular section:</h3>
From the figure, we know that
and the radius is
. So, the are would be calculated with this formula:

Replacing all values:

Remember that 
Therefore, 
Now, the total are of the figure is:

Therefore the area of the symmetrical pool is 
I think 17.2 sorry if im wrong
Using exponential function concepts, it is found that it represents a decay of 0.9%.
<h3>What is an exponential function?</h3>
A decaying exponential function is <em>modeled </em>by:

In which:
- A(0) is the initial value.
- r is the decay rate, as a decimal.
In this problem, the function is:

Hence:


Thus, it represents a decay of 0.9%.
You can learn more about exponential function concepts at brainly.com/question/25537936