# Part d  of the first problem on TakeHome B.



The rate, r, (which is positive) is unknown to us.  We are
given that

3000*r^10 = 12000.    Thus

r^10 = 12000/3000 = 4  and therefore

r^5= sqrt(r^10) = sqrt(4) = 2.

Thus 

num_bact_in_5_hours = r^5 * 12000 = 2*12000 = 24000 .