The question ask to find and choose among the following choices the best function that is correct for Jan's purpose and the new growth rate and the best function would be letter f(x)=4(1.15)5x, growth rate is 15%. I hope you are satisfied with my answer and feel free to ask for more
Volume of a cylinder is V=pi r^2h =42.41
3/4 *42.41=31.81ft
Given a quadratic equation in standard form

The discriminant D

tells the types of roots the equation has.
In this case, we have

Then, the discriminant of this quadratic equation will be

Finally, the value of discriminat is 49 and as he discriminant is greater than zero then this quadratic equation has 2 different real solutions.