In a month of 31 days, third Thursday falls on 16th. What will be the last day of the month?

Since, third Thursday is on 16th. So, for calculation of last day of the month, we should calculate the odd number of days, here total days are 15 till 31.
∴ Odd days = 15/7 = 1
∴ Day on last date of month = friday
That will be 5th Friday.