A rumor is spread in a school. For and , the time at which a fraction of the school population has heard the rumor is given by

(a) Evaluate the integral to find an explicit formula for . Write your answer so it has only one term.

(b) At time , two percent of the school population () has heard the rumor. What is ?

(c) At time , fifty-five percent of the school population () has heard the rumor. What is ?

(d) At what time has ninety-one percent of the population () heard the rumor?

You can earn partial credit on this problem.