Explanation:
Proportionality (mathematics)
In mathematics,
two variable quantities are proportional if one of them is
always the product of the other by
a constant quantity, called the coefficient of proportionality,
or the proportionality constant. In other words, x and y are proportional
if the ratio is constant. We also
say that one of the quantities is proportional
to the other. For example, if the speed
of an object is constant, it travels a distance
proportional to the travel time.
Symbol
The mathematical symbol '∝' is used to indicate that two values are proportional. For
example, A ∝ B.
Inverse proportionality
Two variables are inversely
proportional (or varying inversely, or in inverse
variation, or in inverse proportion or reciprocal
proportion) if one of the variables is directly proportional with the
multiplicative inverse (reciprocal) of the other, or equivalently if their
product is a constant. It follows that the variable y is
inversely proportional to the variable x if there exists a
non-zero constant k such that
The constant can be found by multiplying
the original x variable and the original y variable.
Basically, the concept of inverse
proportion means that as the absolute value or magnitude of one variable gets
bigger, the absolute value or magnitude of another gets smaller, such that
their product (the constant of proportionality) is always the same. (Our
solved example in mathguru.com uses this concept)
For example, the time taken for a journey
is inversely proportional to the speed of travel; the time needed to dig a hole
is (approximately) inversely proportional to the number of people digging.
http://en.wikipedia.org/wiki/Proportionality_(mathematics)
The above explanation is copied from
Wikipedia, the free encyclopedia and is remixed as allowed under the Creative
Commons Attribution- ShareAlike 3.0 Unported License.