Urgent
the depth of water in the port at hinchinbrook is given by: d(t)= 2.6 sin (pi over 6 t) + 13.1, where d is in meters and t is the number of hours since high tide.
use the model to determine how many hours are there between high tides.
if high tide was at midnight, draw a graph to determine during which hours should it be safe for the boats to be in the port and between which hours they would have to stay away from the port. justify answers mathematically

The best way to approach this problem is to look at the graph of the given function. Replace values of x from 1 to 24 to indicate the numbers of hours in a day. As seen on the graph, there is only one point where the port is at high tide. That would be at 1:00 am. 

Looking at the graph, it would be safe for the boats to be in the port when the graph levels off at around 10 to 24. That's from 10 am to before 12 midnight. Then, they would have to stay away between 12 midnight to before 10 am.