Answer:
The answer is 45m/h
Step-by-step explanation:
Since timing is only provided at stage three and four, therefore we can only calculate the average speed at that level.
Speed at step three: \frac{30}{1}=30m/h
Speed at step four: \frac{30}{0.5h} =60miles/h
Average speed:
\frac{30+60}{2}=45miles/h