🔍 Key Concepts

• Recall how standard time zones are generally spaced in 15° increments of longitude. • Understand that a time zone description (like -7 or -8) refers to hours offset from Greenwich Mean Time (GMT/UTC). • Think about the central meridian of each time zone and how the zone boundaries are usually placed halfway between central meridians.

💭 Think About

• First, determine the central meridian for zone description -7 and for -8 based on the idea of 15° per hour from the prime meridian. • Next, find the midpoint in longitude between those two central meridians; that midpoint is the dividing meridian between the two zones. • Compare that midpoint longitude (and its hemisphere, E or W) with each of the answer choices to see which one matches the expected location.

✅ Before You Answer

• Be sure you are using the correct sign convention: negative zone descriptions are generally west of Greenwich. • Verify that the 15° per hour spacing is applied from 0° (Greenwich) correctly before you compute the boundary. • Double-check whether the answer choice longitude is east or west, and ensure it matches where zones -7 and -8 should be located (in terms of hemisphere).