Proportion and Inverse Proportion

Proportion and Inverse Proportion

GCSE(F), GCSE(H),

If two variables are in Direct Proportion, then as the value of one variable increases, the other variable also increases.

If two variables are in Inverse Proportion, then as one variable increases, the other variable falls.

The relationship between the two variables in inverse proportion is `x text( is related to ) frac(1)(y)`.

Examples

1. Two variables, `x text( and ) y`, are known to be in direct proportion. The value of `x` is doubled. What happens to the value of `y`?

Answer: It will double

As the two values are in direct proportion, then one value will increase at the same rate as the other.

2. Two variables, `x text( and ) y`, are known to be in inverse proportion where `x = frac(1)(y)`. What happens to the value of `y`, if the value of `x` is halved?

Answer: It will double

As the two variables are in inverse proportion, then halving one will double the other, and vice versa.