A hiker walks 6 km due north in 2 h and then 4 km due south in 1 h.
(i) Taking north as the positive direction, state the sign (positive, negative or zero) of the hiker’s average velocity for the whole trip.
(ii) Without performing any detailed calculation, say whether the hiker’s average speed is greater than, equal to, or less than the magnitude of the average velocity. Give a reason for each part.