Question

calculate the longitude of the position of a ship whose navigation officer observes GMT as 21.20 hrs, when the local time is 12 noon

Answer 1

1°change =15minutes
change in hours is 21:20-12:00=9hrs 20 minutes
change in °= change in time/15
(9×60)+20=560
∴change in ° =560/15
=37.33°
the ship is 37.33° west

Answer 2

Geographically, each degree of shift in the longitude, there will be a time difference of 4 minutes of time.

GMT is the Greenwich Mean Time, which is the coordinated universal time (UTC), used as a reference to calculate time zone across nations in the world and the difference of timings.

In the given scenario, GMT is 21.20 hrs and local time at the position of the ship is 12 noon.

This shows that the time zone at the ship's location is 9 hours 20 minutes behind GMT. So, the ship is located in west direction of the prime meridian.

9 hours 20 minutes is 9*60 + 20 = 560 minutes

To convert to degree, lets divide by 4.

So, 560/4 = 140°

Final answer:

Longitude at the location of the ship is 140° West