Step 1: Find out the difference in longitudes between two places given.

Step 2: Convert or change the difference in longitude to time, if the difference in degrees is more than 15°, multiply it by 4 minutes.

Step 3: Adjust the time according to the position of the longitude if it is east, we add but if it is west, we subtract time.

Example 1: What is the local time at Madres in India on longitude 80°E, if local time in Yokadouma in Cameroon on longitude 15°E is 4 p.m.?

Solution

 Step 1: Longitudes difference = 80°-15° = 65°

Step 2: Convert longitude difference to time: 65°*4mins = 260mins = 4hrs20mins

Step 3: Add or subtract time

4hrs20mins + 4pm = 8:20pm

Because longitude 80°E is in the East.

Example 2: What is the local time in Baghdad 45°E, 35°N when it is noon in Bombay 75°E, 18°N.

Solution

1) 75°- 45° = 30°

2) 30°/15° = 2hrs or (30°*4mins)/60mins = 2hrs

3) 12 noon - 2hrs = 10 am

Exercices

1. If the time in Accra (Ghana) on longitude 0° is 12noon. What will be the local time in Philadelphia (U.S.A) on longitude 70°W.?
2. What is the local time of Yaoundé 15°E and 5°N, when G.M.T is 8:00 am?

The longitude difference for a town in the East and another in the west is obtained by adding the longitudes.