Yes, yes it is; well done.
The jet has gained on the small plane at the rate of 10 miles per minute, so is flying 600 miles per hour faster. (There are 60 minutes in an hour.)
Since the jet is flying twice as fast as the smaller plane, the small plane's speed is the same as the difference in speed: 600 mph.
The jet's speed is double that, 1200 mph.
- small plane: 600 mph
- jet: 1200 mph
S represents the best distance from 1 and 0 to represent 33 1/3%
