A company begins an Internet advertising campaign to market a new phone. The percentage of the target market that buys a product is generally a function of the length of the advertising campaign. The estimated percentage is given by
f(t) = 100(1 - e-0.04t),
Where t is the number of days of the campaign
a) Graph the function.
b) Find f (25), the percentage of the target market that has bought the phone after a 25-day advertising campaign.
c) After how long will 90% of the target market have bought the phone?