SOLUTION: The count in a bacteria culture was 500 after 20 minutes and 1,200 after 30 minutes. Assuming the count grows exponentially, (a) what was the initial size of the culture? (b) Find

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: The count in a bacteria culture was 500 after 20 minutes and 1,200 after 30 minutes. Assuming the count grows exponentially, (a) what was the initial size of the culture? (b) Find       Log On


   

Question 1121857: The count in a bacteria culture was 500 after 20 minutes and 1,200 after 30 minutes. Assuming the count grows exponentially, (a) what was the initial size of the culture? (b) Find the doubling period. (c) Find the population after 105 minutes. (d) When will the population reach 13,000?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
y=a%2Ab%5Ex
-
500%2Ab%5E10=1200
b%5E10=2.4
10%2Alog%28%28b%29%29=log%28%282.4%29%29
log%28%28b%29%29=log%28%282.4%29%29%2F10
b=1.0915
-
y=a%2Ab%5E1.0915

a%2A1.0915%5E30=1200
a=1200%2F%281.0915%5E30%29
highlight_green%28a=87%29-------initial count

-