SOLUTION: A scientist started his experiment with 5,000,000 cells. He noticed that 45% of the cells die every minute. How much time does it need to be less than 1,000 cells?

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Question 1101972: A scientist started his experiment with 5,000,000 cells. He noticed that 45% of the cells die every minute. How much time does it need to be less than 1,000 cells?
Found 2 solutions by josgarithmetic, ankor@dixie-net.com:
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
45% die each minute; 55% still live each minute.
p for population living
n for number of minutes pass
p=5000000%2A0.55%5En

5000000%2A0.55%5En=1000
5000%2A0.55%5En=1
0.55%5En=1%2F5000
0.55%5En=0.0002
log%28%280.55%5En%29%29=log%28%280.0002%29%29
n%2Alog%28%280.55%29%29=-3.6999
n=-3.6999%2F%28-0.25963%29
highlight%28n=14%261%2F4%29

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A scientist started his experiment with 5,000,000 cells.
He noticed that 45% of the cells die every minute.
How much time does it need to be less than 1,000 cells?
:
there will be 55% of the cells left after each minute
let = time in minutes
5000000*.55^t = 1000
.55^t = 1000%2F5000000
.55^t = .0002
use natural logs
t = ln%28.0002%29%2Fln%28.55%29
t = 14.24 ~ 15 min they will be less than 1000 cells
:
:
Check 5000000*.55^15 = 637 cells