If the height of the tide at low water is 0.0 feet, the range is 9.0 feet, and the duration is 06h 00m. What is the height of the tide 02h 12m before high water ?

Correct Answer: Option A — 6.3 feet

Applying the standard cosine curve (or Twelve-Foot Rule) for tide heights, a 9-foot range over 6 hours gives the height at 2 hours 12 minutes before high water as 6.3 feet above mean low water.