Need help bulk modulus problem

1. Feb 15, 2006

hannsparks

A solid ball of a special plastic material is to be used as a replacement joint for a patient’s hip. The mass per unit volume density of the ball is 900 kg/m3 and its radius is 1.5 cm. The ball is subjected to a test in which it is subjected to an increase in external pressure of 2 X 10 8 N/m2. The Bulk modulus of the ball is 2 X 10 9 N/m2.
Assuming that the ball is compressed uniformly during this test, find the mass
per unit volume density of the ball in its compressed state. The volume
formula for a sphere of radius r is 4/3 pi r 3 .

what Ive done so far:
Volumem initial =1.414e-5

change p= -B changeV/initial V

change V=-1.414e-6

mass of ball= 900 x 1.414e-5=.012735

Im not really sure hwat to do next I tried to solve for density of the ball using the mass .012735 and the volume (change and then intitial) but both answers were wrong I know the answer is supposed to be 1000kg/m3 according to the book but im not getting that