(a) For motion from A to B:

Distance covered = 300 m

Displacement = 300 m.

Time taken = 150 sec.

We know that, Average speed = Total distance covered ÷ Total time taken

= 300 m ÷ 150 sec = 2 ms^{-1}

Average velocity = Net displacement ÷ time taken

= 300 m ÷ 150 sec = 2 ms^{-1}

(b) For motion from A to C:

Distance covered = 300 + 100 = 400 m.

Displacement = AB - CB = 300 - 100 = 200 m.

Time taken = 2.5 min + 1 min = 3.5 min = 210 sec.

Therefore, Average speed = Total distance covered ÷ Total time taken

= 400 ÷ 210 = 1.90 ms^{-1} .

Average velocity = Net displacement ÷ time taken

= 200 m ÷ 210 sec = 0.952ms^{-1} .