Mathematics for IGCSE & O level - Ratio And Proportion (Section 6 - No. 11)
If two quantities are inversely proportional, then
As one quantity increases, the other decreases.
The product of the quantities is constant.
As one quantity decreases, the other decreases.
The ratio between them is constant.
Forklaring
Inverse proportion means the increase in one causes decrease in the other, maintaining a constant product.