Answer:
Initial populatin: 3652 bacteria
Explanation:
The rate is 85% per hour.
Let x be the initial population.
After 1 hour:
x1=x+85%×x=x+0.85x=1.85 x
After another hour:
x2=x1+85%×x1=1.85 x1=1.85² x
But x2=12500.
12500=1.85² x
x=12500/1.85²=3652.3 bacteria
Since you cannot have fractions of a bacteria, the initial population was 3652.