Which of these are examples of direct proportion?
(i) Cost price to grocery.
(ii) Time required in completing a work to the number of workers doing that work.
(iii) Distance covered and time taken to cover that distance when speed is constant.
(i), (iii)
(i) The cost price increases as the amount of grocery purchased increases and vice-versa.
(ii) Time required in completing a work is inversely proportional to the number of workers doing that work. If workers are more in number, then work can be done in less time and vice-versa.
(iii) If speed is constant, then as the distance covered increases, the time taken to cover that distance also increases and vice-versa.