JAMB Geography 2020 Paper

Concept:Local time is earlier to the west of the Greenwich Meridian, so a time difference corresponds to a longitude difference of $15^\circ$ per hour.Explanation:Greenwich Mean Time is $6{:}00$ pm, while town Y has $12{:}00$ noon.Time difference = $6{:}00$ pm $- 12{:}00$ noon $= 6$ hours.Longitude difference $= 6 \times 15^\circ = 90^\circ$.Since town Y's time is behind GMT, it lies to the west of the Prime Meridian.Therefore, the longitude of town Y is $90^\circ$ W.Answer:A. $90^\circ$ W