The pressure, P (in lbs/ft2 ), in a pipe varies over time. Five times an hour, the pressure oscillates from a low of 90 to a high of 230 then back to a low of 90. The pressure at t = 0 is 90.

a) Graph P = f(t), where t is the time in minutes. Label your axes. Be sure to show at least 2 full cycles. (3 pts.)

b) Find a possible formula for P = f(t). (3 pts.)

c) Find the time when the pressure first equals 115 lbs/ft2 . (2 pts.)