The radius of the base of a cylinder is decreasing at a rate of $12$ kilometers per second. The height of the cylinder is fixed at $2.5$ kilometers. At a certain instant, the radius is $40$ kilometers. **What is the rate of change of the volume of the cylinder at that instant (in cubic kilometers per second)?** [[☃ radio 1]] *The volume of a cylinder with radius $r$ and height $h$ is $\pi r^2h$.*