A motor-boat travels 30km downstream and then the same distance upstream in a river running at 3km h−1. The upstream journey takes 1 hour more than the downstream journey.
a. (i) If the speed of the boat in still water is vkm h−1, obtain an equation in v that models the situation.
b. (ii) Solve the equation to find the two possible values of v.
c. (iii) Keeping in mind the physical conditions of the motion, select the acceptable value of v and state the speed of the boat in still water.