This is a geometric sequence but you don't know the growth factor, so you would solve for it first.
2400= 2000(x)^8
1.2= x^8
x= 1.02305188
You can round depending on what your teacher prefers.
Now you can plug in your growth factor and solve.
A(19)= 2000(1.02305188)^19
A(19)= 2000(1.54189747739)
A(19)= 3083.79495477
After 19 hours, 3,084 bacteria will be present.