121. At 1730 zone time, on 3 March, your DR position is LAT 16°00'S, LONG 80°00'W. You are steering 000°T at a speed of 7.5 knots. What is the zone time of sunset?

The correct sunset zone time is 1843, determined by finding the Local Mean Time (LMT) of sunset in the Nautical Almanac for the given date and latitude, then adding 20 minutes to account for the longitude difference between the ship's position and the zone meridian.