How many Standard Time Zones will a country with a longitudinal extent of 155° have?

Analyze the question: The Earth rotates 360° in 24 hours, so each standard time zone covers 15° of longitude (1 hour = 15°). We need to find how many time zones a country spanning 155° of longitude will have.

Concept: Number of time zones = longitudinal extent ÷ 15°

Solution:

Number of zones = 155° ÷ 15° = 10.33

Since a fraction of a zone still falls within another time zone, we round up to the next whole number:

10.33 → 11 time zones

(Ten full zones cover 150°, and the remaining 5° falls into an eleventh zone.)

Checking the options:

• A. 9 is too few, since 9 × 15 = 135°, which doesn't cover 155°.
• B. 11 is correct, since it covers the full 155°.
• C. 15 and D. 16 are far too many.

Exam tip: For "how many time zones" questions, divide the longitudinal extent by 15° and round up if there is a remainder. For "time difference" questions, multiply the longitude difference by 4 minutes per degree.