**Question:**

Which of the following quantities vary inversely as each other?

(i) The number of *x* men hired to construct a wall and the time *y* taken to finish the job.

(ii) The length *x* of a journey by bus and price *y* of the ticket.

(iii) Journey (*x* km) undertaken by a car and the petrol (*y* litres) consumed by it.

**Solution:**

(i) If the number of men is more, the time taken to construct a wall will be less. Therefore, it is in inverse variation.

(ii) If the length of a journey is more, the price of the ticket will also be more. Therefore, it is not in inverse variation.

(iii) If the length of the journey is more, the amount of petrol consumed by the car will also be more. Therefore, it is not in inverse variation.

Thus, only (i) is in inverse variation.