Determine how long it will take an airplane to travel 2000 miles if it flies 200 miles per hour, 400 miles per hour, and 600 miles per hour.

I will use 'hr' to mean hour and 'hrs' to mean hours.

The airplane flies:

200 miles per hr

400 miles per hr

600 miles per hr

Average speed = Total distance : total time

= (200 + 400 + 600) miles : 3hrs = 400miles/hr

Time = Distance : Average speed

= 2000miles : 400miles/hr = 5hrs