Question 821663:  Cholera is an infectious disease caused by the bacterium Vibrio cholera. This bacteria is known to grow exponentially. If you begin with a laboratory sample of 100 bacteria at 12:00 noon, and measure that there are 400 bacteria in your sample at 1:00pm the same day, how many bacteria would you expect in your sample at 3:00pm? Round answer to nearest unit. 
 Answer by TimothyLamb(4379)      (Show Source): 
You can  put this solution on YOUR website! --- 
f(t)= P*e^(tk) 
where: 
P = initial value 
k = growth or decay factor per unit of time 
t = time 
--- 
at t=1 hour, f(1) = 400 bacteria 
f(1) = 400 = 100*e^k 
--- 
400/100 = e^k 
4 = e^k 
ln(4) = ln( e^k ) 
ln(4) = k 
k = 1.3862944 growth factor per hour 
--- 
at t=3 hours, f(3) = ? 
f(3) = 100*e^(3k) 
f(3) = 100*e^(3k) 
f(3) = 100*64 
--- 
answer: 
at 3 pm expect 6400 bacteria 
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