An FM radio station launches an advertising campaign in order to increase the number of daily

listeners. The station currently has 27, 000 daily listeners, and the management expects the

number of daily listeners, (), to grow at the rate of

() = 60

12

listeners per day, where

is the number of days since the campaign began. How long should the campaign last if the

station wants the number of daily listeners to grow to 41, 000?