The relative growth rate for a certain type of bacteria population is 85% per hour. a small culture has formed and in just 2 hours the count shows to be 12,500 bacteria in the culture. what is the initial number of bacteria in the culture?

Let us assume the initial number of bacteria in the culture = x
After 1 hour,
The number of bacteria = 185x/100
                                      = 1.85x
After 2 hours,
The number of bacteria = (185 * 1.85x)/100 
                                      = 3.42x
So
3.42x = 12500
x = 12500/3.42
   = 3654.97
   = 3655
From the above deduction, we can conclude that the initial number of bacteria in the culture is 3655.