If b ∝ a³ and a increases in the ratio of 2 : 3, let us find in what ratio b will be increased.

If x ∝ y² and y = 2a when x = a; x and y let us find the relation between x and y.

If x ∝ y, y ∝ z and z ∝ x, let us find the product of three non zero constants.

If and let us find if there be any relation of direct or inverse variation between x and z.

If x ∝ yz and y ∝ zx let us show that z is a non zero constant.