An important programme was to be broadcast from Mumbai at 7.30 p.m. This was heard by some Indian sailors near Ivory Coast in West Africa at 20°W longitude. What was the local time there ?

An important programme was to be broadcast from Mumbai at 7.30 p.m. Th

1.	An important programme was to be broadcast from Mumbai at 7.30 p.m. This was heard by some Indian sailors near Ivory Coast in West Africa at 20°W longitude. What was the local time there ?
Answer» According to the Indian Standard Time 7.30 p.m. based on 82 1/2° E. Longitude was the time at Mumbai. The longitudinal difference between Mumbai and Ivory Coast at 20° W is 82.5 + 20 = 102.5. So 102.5 × 4 = 410.0 minutes = 6 hours 50 minutes, i.e. the time will be 6 hours 50 minutes less than 7.30 p.m. So the time will be 12.40 p.m