[填空题]
A person jogs eight complete lly.hd9/+ ea ;v4qpxrqaps around a y xh vxo:a,p+blc dk9;0q0wlj.af kr:6r8r 8bquarter-mile ($1 \; mile = 1609 \; m$) track in a total time of 20.0 min. Calculate (a) the average speed $m/s$ and (b) the average velocity $m/s$