A mechanism for recording the distance covered by the bicycle, as shown in Fig.15.32, is as follows: There is a fixed annular wheel A of 22 teeth and another annular wheel B of 23 teeth, which rotates loosely on the axis of A. An arm driven by the bicycle wheel through gearing not described, also revolves freely on the axis of A and carries on a pin at its extremity two wheels C and D, which are integral with one another. The wheel C has 19 teeth and meshes with A and the wheel D with 20 teeth meshes with B. The diameter of the bicycle wheel is 0.7 m. What must be the velocity ratio between the bicycle wheel and the arm, if B makes one revolution per 1.5 km covered?