Jharkhand PSC Prelim Exam 2006 Solved Paper

(3) When 82°30' east longitude which is considered as standard time of India. When it is 12.00 PM. India is ahead of +5 hr 30 min from Green which time that passes near London. It is called zero longitude either east or west.
This is called Green which time of the world i.e the time of all the countries of the world is calculated from this Green which time.