A student wanting to catch fish to sell at a local market on Sunday has discovered that more fish are in the water at the end of the pier when the depth of water is greater than 8.5 metres.
The depth of the water (in metres) is given by d=7+3*sin((π/6)t), where t hours is the number of hours after midnight on Friday.
a. Between what hours should the student be on the pier in order to catch the most fish?
b. If the student can fish for only two hours at a time, when should she fish in order to sell the freshest fish at the market from 10.00am on Sunday monday?