If A Plane Left On Time At Noon On Monday And It Arrived At Its Destination At 8:16 PM The Same Day Which Was 16 Minutes Late How Many Seconds Did The Plane Fall Behind Every Fifteen Minutes?

The scheduled arrival time should have been 8:00pm with a flight time of 8 hours.
8 hours = 32 periods of 15 minutes.
Over 32 periods the plane lost 16 minutes
Over 1 period the plane lost ¹⁶/₃₂ minutes = 30 seconds.
The plane fell behind by 30 seconds every 15 minutes.