Question

A sphere is increasing in volume at the rate of 3(pi) cm^3/sec. At what rate is the radius changing when the radius is 1/2 cm? The volume of a sphere is given by V=4/3(pi)r^3.
A. pi cm/sec
B. 3 cm/sec
C. 2 cm/sec
D. 1 cm/sec
E. .5 cm/sec

Answer 1

from you formula for v,

dv/dt = 4pi r^2 dr/dt

now plug in the numbers.

Answer 2

B. 3 cm/s