Answer
a. 197 m/s.
b. 169 m/s.
Work Step by Step
The average velocity is $v_{av}=\frac{\Delta y}{\Delta t}$.
Let the positive direction be upward.
a. $v_{av}=\frac{\Delta y}{\Delta t}=\frac{1000m-63m}{4.75s}=197m/s$
b. $v_{av}=\frac{\Delta y}{\Delta t}=\frac{1000m-0m}{5.90s}=169m/s$
