To convert 900 kilometers per hour to miles per hour using the conversion ratio of 1 kilometer equals about 0.62 miles, you can use the following calculation:
\[ \text{Speed in miles per hour} = \text{Speed in kilometers per hour} \times \text{Conversion factor} \]
\[ \text{Speed in miles per hour} = 900 , \text{km/h} \times 0.62 , \text{miles/km} \]
\[ \text{Speed in miles per hour} = 558 , \text{miles per hour} \]
So the airplane’s speed in miles per hour is 558.