Upper bound for time is found using the lower bound on average speed and upper bound on track length.
I'm not sure what correct to one decimal place means.
If this means the digit is correct, then the average speed lower bound is 5.0m/s.
If it means correct rounded to 1 decimal place, then the average speed lower bound is 4.95 m/s.
If it means with an error of 0.1 m/s, then 4.9 m/s.
Upper bound on track distance is 401m.