The depth of the water at the end of a pier changes periodically along with the movement of tides. On a particular day, low tides occur at 12:00 am and 12:30 pm, with a depth of 2.5 m, while high tides occur at 6:15 am and 6:45 pm, with a depth of 5.5 m. Let t = 0 be 12:00 am.Graph the equation d = -1.5 cosine left-bracket StartFraction 4 pi over 25 EndFraction t right-bracket + 4 that models the situation using a graphing calculator and use it to answer the following questions.