A certain bacteria triples in a Petri dish every hour. Which formula should be used to determine the bacteria after x hours assuming uninhibited growth and there was initially 500 colonies.

a
500\ \left(1.03\right)^x

b
500\ \left(3\right)^x

c
500\ \left(2\right)^x

d
500\ \left(1.02\right)^x