A body travelling along a straight line traversed one third of the total distance with velocity 4 m/s. The remaining part of distance was covered with a velocity $2 m/s$ for half the time and with velocity 6 m/s for other half of time. the mean velocity averaged over whole time of motion.

Question

$$(a)\; 5 m/s \quad (b)\;4 m/s \quad (c)\;4.5 m/s \quad (d)3.5m/s$$