Previous Year Question
Into how many major time zones is the world divided?
Correct Answer: C
Detailed Solution
Under the standard geographical system, the Earth is considered to be divided into 24 major time zones. The Earth rotates through approximately 360° in 24 hours. Therefore, ideally, the difference in longitude corresponding to one hour is:
360° ÷ 24 = 15°
Thus, each ideal time zone is approximately 15° of longitude wide. According to the U.S. National Institute of Standards and Technology (NIST), the basic concept of time zones divides the Earth into 15° sections of longitude, producing 24 time zones for the 24 hours of a day.
In practice, however, time-zone boundaries do not always follow exact 15° meridians. They are often adjusted according to political boundaries, administrative convenience and local requirements, and some regions use offsets of half an hour or even 45 minutes.