You have steamed 432 miles at 18 knots and burning 406 barrels of fuel per day. You must decrease your consumption to 221 barrels per day with 190 miles left in your voyage. What must you reduce your speed (kts) to in order to burn this amount of fuel?

Correct Answer: Option B — 20.0

Applying the fuel consumption cubic law, fuel per distance or time ratios allow calculating the required speed adjustment. Reducing burn rate from 406 to 221 barrels per day over remaining passage distance requires dropping speed to 20.0 knots under shipboard engineering performance formulas.