SOLUTION: I need help learning how to do this problem: A culture of bacteria doubles after 9 hours. What proportion of the original number of bacteria (Q sub 0) will be present after 1

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: I need help learning how to do this problem: A culture of bacteria doubles after 9 hours. What proportion of the original number of bacteria (Q sub 0) will be present after 1      Log On


   

Question 873432: I need help learning how to do this problem:
A culture of bacteria doubles after 9 hours.
What proportion of the original number of bacteria
(Q sub 0)
will be present after 18 hours?
Thank you for any help on how to set it up!
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
You start out with some amount of bacteria (Q0)


It doubles after 9 hours (Q0 ----> 2*Q0)


After another 9 hours (now at 9+9 = 18 hours), it doubles again: 2*Q0 ----> 4*Q0


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We've gone from Q0 to 4*Q0


Divide to get (Q0)/(4*Q0) = 1/4


So 1/4 of the population of bacteria after 18 hours is the original amount you started out with.