Solution:Total duration of the class from 11:00 am to 2:27 pm = 3 hr 27 min = 207 minutesAfter every period a rest of 5 minutes is given to the student.
So, there will be 3 rest in 4 periods.
∴ Rest time = 3 × 5 = 15 minutes
Remaining time = 207 - 15 = 192 minutes
There 192 minutes will divide in 4 equal duration period.
∴ Exact duration of each period = 192/4 = 48 minutes