Ride-O is testing its new product which is a mini-car that is designed for kids. The test aims to study the changes in the velocities of the mini-car at a 5-s interval. What is the average acceleration in each of the following intervals? Consider the convention that the east direction is positive. 

(i) At the start of the interval, the mini-car is moving 1.5 m/s to the east, and at the end, it is moving to the east at 1.2 m/s. 

(ii) At the start of the interval, the mini-car is moving due west at 1.75 m/s, and at the end, it is moving at 2.0 m/s, still towards the west. 

(iii) At the start, the mini-car is moving to the east at 1.9 m/s, and at the end, it is moving to the west at 1.9 m/s.