Exponential Growth Question

Question

I'm doing exponential growth. Initial population is 10 bacteria. Doubles every 1.5 hours. 

 

The model for the culture after t hours is: n(t) = n2^t/a

 

For this culture it should be n(t) = 10 x 2^t/1.5

 

However, the correct answer is n(t) = 10 x 2^2t/3

 

Can someone explain why 2^t/1.5 becomes 2^2t/3. 

Answer 1

t / 1.5 = 2t / 3          The 1.5 was converted to an integer.