The fish population in a certain lake rises and falls according to the formula F = 4000(26 + 12t − t^2). Here F is the number of fish at time t, where t is measured in years since January 1, 2002, when the fish population was first estimated. (a) On what date will the fish population again be the same as it was on January 1, 2002? (b) By what date will all the fish in the lake have died?