|:l Elphaba and Walt are planning to break out of prison. They would like to escape no later than 20 hours after devising their plan, and they would like to attempt their escape during the noisiest part of the day. Let N (t) be the noise level (in decibels) in the prison t hours after Elphaba and Walt have devised their escape plan. On the interval [0, 20], a formula for N (t) is given by 1 N(t) = 60 + 1.011900 where p(t) = t3 9732 + 56t + 200. a. I:| Find the values of t that minimize and maximize N (t) on the interval [0, 20]. Use calculus to nd your answers, and be sure to show enough evidence that the points you nd are indeed global extrema. (J global min(s) at t =l global max(es) at t =