Why time zones are 30 minutes?

Related questions

1. Is Australia behind or ahead of us?
2. How long is the flight to Australia from UK?
3. Does it ever snow in Australia?
4. What is NSW famous for?
5. What country is a day ahead of us?
6. What is the hottest month in Melbourne Australia?
7. Why does Australia have daylight savings?
8. Is it expensive to travel to Australia?
9. How many cities are there in NSW?
10. What month is the hottest in Australia?

Tags

1. #european
2. #hours
3. #opposed
4. #minutes
5. #eastern
6. #therefore
7. #became
8. #delhi
9. #other
10. #found
11. #adopting
12. #example
13. #decided
14. #india
15. #between
16. #meridians
17. #halfway
18. #themselves