The cylindrical hot tub is being emptied at a rate 5 ft^3 / 2 minutes or (5/2) ft^3 per minute.

The height of the tub is 4 feet and the radius of the tub is 3 feet.

For a cylinder with a height h and a radius r, the volume is given by pi*r^2*h. Substituting the values r = 3 and h = 4, we get

V = pi*3^2*4

=> V = pi*9*4

=> 36*pi ft^3

The rate at which the tub is being emptied is (5/2) ft^3/minute.

This gives the time required to empty the tub as 36*pi / (5/2)

=> pi*36*2/5

=> pi*14.4 minutes

**The required time to completely empty the tub is 14.4*pi minutes.**