An airplane 30,000 feet above the ground begins descending at a rate of 2,000 feet per minute. write an equation to model the situation. find the altitude of the plane after 5 minutes.

The volume of a spherical hot air balloon v(r) = 4 3 ? r3 changes as its radius changes. the radius is a function of time given by r(t) = 3t. find the instantaneous rate of change of the volume with respect to t at t = 2.