The average speed is 50 mph, and it varies by 6 mph.
To find the lowest speed, subtract the variation from the average speed:
- Lowest speed = 50 mph - 6 mph = 44 mph
To find the highest speed, add the variation to the average speed:
- Highest speed = 50 mph + 6 mph = 56 mph
Therefore, the lowest speed is 44 mph and the highest speed is 56 mph.
So, the answer is: 44 mph and 56 mph.