A delivery robot moves successively to the following positions on a warehouse floor measured in metres from the origin: A(1.5,4), B(−3,−1), C(2,−4.5), D(−1.5,23) and E(0,0.5). Answer the questions that follow.
(i) Arrange the five positions in order from the least to the greatest ordinate.
(ii) Arrange the same positions from the least to the greatest abscissa.
(iii) List the consecutive moves in which the robot travelled strictly northward (increase in ordinate) while also moving westward (decrease in abscissa). Give reasons for each move you list.