Answer:
Hence, option D is correct.
(i.e. Average speed is 5/2 miles/hour)
Step-by-step explanation:
We are asked to find the average rate of speed over the interval [9, 11].
We know that average speed is given as the ratio of total distance over total time.
the distance when time=9 hours is 6 miles.
and the distance when time=11 hours is 11 miles.
Hence, average speed is given as:
[tex]Average speed=\dfrac{Total distance}{Total time}\\\\Average speed=\dfrac{11-6}{11-9}\\\\Average speed=\dfrac{5}{2}[/tex]
Hence average speed is 5/2 miles/hour.