Answer:
3600 bacterias
Explanation:
From P = P'e^(-kt), where
P = final population
P' = initial population
k = decay constant
t = time in hrs
Substituting we have
200 = 170000 x e^(-42k)
1/850 = e^(-42k)
We take natural log (Ln) of both side
Ln (1/850) = Ln (e^(-42k))
-6.745 = -42k
k = 0.16059.
For amount remaining after 24 hrs we find P
P = 170000 x e^(-0.16059x24)
P = 170000 x e^-3.85416
P = 170000 x 0.02119 = 3602.3
Approximately 3600 bacterias.