🔍 Key Concepts

• Zone description (ZD) and how it relates to time zones east and west of Greenwich • The fact that each time zone usually spans 15 degrees of longitude • How the sign of the zone description (+ vs -) relates to east or west longitude

💭 Think About

• First, figure out what longitudes generally correspond to ZD +4 and ZD +5 based on the 15-degree-per-hour rule. • Then determine the approximate midpoint (dividing meridian) between those two adjacent zones. • Think about whether positive zone descriptions (+) usually apply to longitudes east or west of Greenwich, and use that to decide if you should be looking at east or west longitudes.

✅ Before You Answer

• Confirm which longitudes roughly define the center of ZD +4 and ZD +5 (e.g., 60°, 75°, etc.). • Verify that the meridian you choose is exactly halfway (7°30') between those central meridians. • Double-check that the sign (+4, +5) correctly matches east or west of Greenwich for the longitude you pick.