Question

At a certain time of the year the depth of water d(m), in the harbour at Bunk Island is given by the rule d=3+1.8 cos(pi/6 * t), where t is the time in hours after 3 am.A passenger ferry operates between Main Beach and Bunk Island. It takes 50 minutes to
go from Main Beach to Bunk Island. The ferry only runs between the hours of 8 am
and 8 pm and is only able to enter the harbour at Bunk Island if the depth of water is at
least 2 metres.The time to go from Bunk Island to Main Beach is also 50 minutes.

Answer 1

The minimum time the ferry takes at Bunk Island harbour is 5 minutes. The minimum time at Main Beach
is also 5 minutes.