A population of bacteria grows by 13% every hour. If you know the population after 6 hours was P, which expression tells you the population after 9 hours?
If the population grows by 13% every hour, then the population after 6 hours would be P * 1.13^6.
To find the population after 9 hours, we need to multiply the population after 6 hours by an additional growth factor of 1.13.
So the expression that tells you the population after 9 hours is P * 1.13^6 * 1.13.