Answer
a) $4.76$
b) $2.68$
c) He is slowing down.
Work Step by Step
a) Apply the rule such as
The average rate is given as: $\dfrac{f(b)-f(a)}{b-a}$ where $a \leq b$
$\dfrac{f(152)-f(68)}{152-68}=\dfrac{800-400}{84}=4.76$
b) Apply the rule such as
The average rate is given as: $\dfrac{f(b)-f(a)}{b-a}$ where $a \leq b$
$\dfrac{f(412)-f(263)}{412-263}=\dfrac{1600-1200}{149}=2.68$
c) Likewise on comparing between the average speed, we can notice that that he is slowing down.
