Inverse Variation Formula

Inverse variation formula refers to the relationship of two variables in which a variable increases in its value, the other variable decreases and vice-versa. In other words, the inverse variation is the mathematical expression of the relationship between two variables whose product is a constant.

Formula for Inverse Variable

The Inverse Variation Formula is,

y ∝ (1 ⁄ x)

⇒ y = (k ⁄ x)

Here, K is the constant of proportionality.

Solved Example Question

Question 1: If y varies inversely with x and when y = 100, x = 30. What is the value of y when x = 10?

Solution:

Given, y = 100 x = 25

The inverse variation formula is,

y = (k ⁄ x)

100 = (k ⁄ 30)

k = 100 × 30

k = 3000

Now, x = 10 k = 3000

y = (k ⁄ x)

y = (3000 ⁄ 10)

y = 300


Practise This Question

Assuming that the petrol burnt in a motor boat varies as the cube of its velocity, the most economical speed, when going against a current of c km/h is