1. Local time from GMT

Steps

• Calculate the difference in longitudes
• Calculate time
• Adjust time

2. Longitudes from local time

Steps

• Calculate difference in time
• Calculate longitude
• Adjust longitude

Examples:

1. What is the local time of Yaounde 15^oE, 5⁰N when GMT is 10:00am?

Solution

Longitude difference=15^oE – 0^o

                                     = 15^o

Time= if 1^o= 4minutes

                15^o= (15 × 4)mins

                          =60min or 1hr

Local time in Yaounde= 10:00am + 1hour

                                        =11:00am

2. What is the longitude of Cairo whose local time is 4pm when GMT is 2pm?

Solution

Time difference= 4pm-2pm= 2hrs or 120min

Longitude difference= if 1^o is 4min

                                           X  is 120min

             X= 120/4

                     =30^o

Longitude of Cairo= 30^o+0^o= 30^oEast

N.B;    1^O=4MINUTES

• When local time is greater than GMT longitude is to the east
• When GMT is greater than local time longitude is to the west