.8 = 1 - e^-.01t
-.2 = -e^-.01 t
ln .2 = -.01 t
t = -(ln .2)/.01 = 161
A company begins a radio advertising campaign in Chicago to market a new soft drink. The percentage of the target market that buys a soft drink is estimated by the function f(t)=100(1-e^-0.01t), where t is the number of days of the campaign. After how long will 80% of the target market have bought the soft drink?
1 answer