Originally Posted by PornoPlopedia

thank you for wasting my time on this problem

I started it at least. Maybe I will finish it later
Here is what I have so far:

we have a time function T(x)= 5(36+x^2)^1/2 + 4(20-x) <=> d (time)= d(distance)/d(speed)

1-Simple, here the crocodile swims only, so we need to solve the time equation for x= 20 meters.
a) T(20) = 5*(436)^1/2 + 0 = 104.403065 Sec

b) Simple, we need to solve for x=0 meters.
T(0)= 110 Sec

2- we need to find the derivative of the time function and then solve for it. Have fun I have work to do