We have the following formula:
[tex]P(t)=10\cdot(1.015)^t[/tex]where t is the amount of minutes we have waited. So in this case we have 12hours, therefore we have waited 12*60=720 minutes
so we have that after 720 minutes the population of bacteria is
[tex]10\cdot(1.015)^{720}=452428.98\approx452429[/tex]so the answer is 452429