You fly 180 nautical miles at a constant ground speed of 90 knots. How long is the flight in hours?

• A. 2 hours
• B. 1 hour
• C. 3 hours
• D. 2.5 hours

Answer: (A)

Time equals distance divided by speed. Here the distance is 180 nautical miles and the speed is 90 knots, which is 90 nautical miles per hour. So the duration is 180 ÷ 90 = 2 hours. Since knots are nautical miles per hour, the units naturally resolve to hours. A quick check: at the same speed, doubling the distance doubles the time, so 180 nm at 90 knots takes 2 hours.