Question 23The graph relates the distance traveled (in miles) to the time elapsed (in hours) on a trip taken by an experimental airplane. During which hour was the average speed of this airplane the largest? first $(0\text{-}1)$second $(1\text{-}2)$third $(2\text{-}3)$ninth $(8\text{-}9)$last $(11\text{-}12)$
