Two values are said to be inversely proportional when the value of one increases, the other decreases. Hence inverse proportionality is expressed in a fraction
y∝[tex] \frac{1}{x} [/tex]
as the value of x increases, the value of y will decrease
This is expressed as an equation using the inverse proportionality constant k
y= k. [tex] \frac{1}{x} [/tex]
or
y=[tex] \frac{k}{x} [/tex]
Hence the fourth option is the correct answer