each time zone is set off GMT (greenwichmeantime) you can break down those time zones into minutes by distance. meaning it is always 420 some where!
There is normally 15 degrees of longitude between each time zone.
Okay... That's the answer that the teachers want in the classroom, but it really only applies "out there" in the middle of the Atlantic, Pacific, Southern or Indian oceans. For the rest of the "dry land" world the answer is much more complicated.
......Warning: Prepare to argue with your teacher! (Print this page if possible.)
When crossing from one time zone to another the local time NORMALLY changes by one hour, or 60 minutes. BUT.... be aware that there are places in the world where time zones change by different numbers of minutes... 15, 30, 45, 90 and even 120 minutes!
Examples: (and there are many, many more...)
(1) When travelling from Columbia to Venezuela the time changes by 30 minutes, even though both countries share a border.
(2) Iran is 30 minutes ahead of Iraq (on its western border) and 90 minutes behind Pakistan (on its eastern border) but all of Iran is just one time zone.
(3) Napal is 15 minutes ahead of India but they share a border.
(4) The South East corner of Western Australia is 45 minutes ahead of the rest of Western Australia.
(5) And my favorite: Vladivostok, Russia is WEST of Japan but has a time zone one hour EARLIER than Japan! So when traveling east from, say, Mongolia you would change the clock AHEAD by 120 minutes (2 hours ) when you reach Vladivostok, Russia, then change your clock BACK one hour when you reach Japan. Strange, but true.
TEACHER ADVISORY: Check out the Related Link below and see for yourself! {click on a region for a close-up map}
http://www.worldtimezone.com/