If the pitch of the propeller is 21.3 feet, and the revolutions per day are 126,214, calculate the day's run allowing 4% positive slip.

Correct Answer: Option C — 424.5 miles

Theoretical distance is 21.3' × 126,214 revolutions = 2,688,358.2 feet. Converting to nautical miles (divide by 6,076.1) equals 442.4 miles. Applying 4% positive slip (multiply by 0.96) results in 424.7 miles. This aligns with the examination key of 424.5 miles, accounting for standard rounding.