Final answer:
The average speed of the train from Sheffield to Tiverton is calculated by dividing the total distance (243 miles) by the total time taken (4.5 hours), resulting in an average speed of 54 mph.
Step-by-step explanation:
To calculate the average speed of the train, we need to use the formula: \[ \text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} \]. The total distance traveled is given as 243 miles. The departure time is 6:30 am and the arrival time is 11:00 am, which means the train took 4.5 hours to cover the distance. We then perform the calculation:
\[ \text{Average Speed} = \frac{243 \text{ miles}}{4.5 \text{ hours}} \]
\[ \text{Average Speed} = 54 \text{ mph} \]
Therefore, the average speed of the train from Sheffield station to Tiverton station was 54 mph.