After a special medicine is introduced into a petri dish containing a bacterial culture, the number of bacteria remaining in the dish decreases rapidly. The number of bacteria decays by a factor of \dfrac{1}{15} 15 1 ​ start fraction, 1, divided by, 15, end fraction every 6.76.76, point, 7 minutes, and can be modeled by a function, NNN, which depends on the amount of time, ttt (in minutes). Before the medicine was introduced, there were 90{,}00090,00090, comma, 000 bacteria in the Petri dish. Write a function that models the number of bacteria ttt minutes since the medicine was introduced.