Line Graph Showing Body Temperature Changes in a Patient

The line graph below shows the change in body temperature of a male patient from \(8.00\) am to \(11\) pm. The temperatures are taken every \(3\) hours. The normal temperature of a person is approximately \(37{}^\circ \mathrm{C}\).

1. State the period of decline of his temperature till it reaches normal.
2. State which is the \(3\) hours period of highest increase in the temperature and state the percentage increase.
3. Calculate the average temperature from \(8\) am to \(11\) pm.