Answer:20.5
Explanation:
I you consider than there is a linear reltionship between p and f, then
![f(p)=a+b*p](https://img.qammunity.org/2020/formulas/mathematics/high-school/5czh9yeq0udo77dijx6a00642es1orzz1w.png)
then, you need to fin out the value of b, and you know that:
![f(5.3)-f(5.3-0.2)=4.1\\f(5.3)-f(5.1)=4.1\\(a+b*5.3)-(a+b*5.1)=4.1\\a+b*5.3-a-b*5.1=4..1\\a-a+5.3b-5.1b=4.1\\0.2b=4.1\\b=4.1/0.2\\b=20,5](https://img.qammunity.org/2020/formulas/mathematics/high-school/yox4f46r9hegqvzeoceh9jdqmlxtzstci7.png)
Then f(p)=a+20.5p
And the derivative, f' which represent the variation rate is b=20.5
Because the derivative of a+nx is b