a.write a function that models an inverse variation situation

Answer 1

Here is an example of a function that models an inverse variation situation:

```python
def inverse_variation(x):
k = 5 # constant of variation
y = k / x
return y
```

In this function, `k` represents the constant of variation. As `x` increases, `y` decreases proportionally. This is a typical example of an inverse variation situation where the relationship between two variables is such that one variable decreases as the other variable increases, and vice versa.