The doubling period of a bacterial population is 20 minutes.

Question

At time t=120 minutes, the bacterial population was 60000. What was the initial population at time t=0 ? Find the size of the bacterial population after 4 hours

Answer 1

A(t) = Pe^rt

2P = Pe^20r and 60000 = Pe^120r

From the first equation, e^20r = 2.

lne^20r = ln2

20r = ln2

r = ln2/20 = 0.0346

60000 = Pe^0.0346(120)

P = 60000/63.56 = 944= population when t = 0

Answer 2