Sometimes
Example:
As the number of DVDs you buy increases the total cost is added by 12$
For example,
1 DVD - 12$
2 DVD - 24$
3 DVD - 36$
...
100 DVD - 1200$
Hence, the relationship is proportionate.
It
introduces the relationship between two variables and is called
correlation. Proportionality or variation is state of relationship or
correlation between two variables It has two types: direct variation or proportion which
states both variables are positively correlation. It is when both the
variables increase or decrease together. On the contrary, indirect variation or proportion indicates
negative relationship or correlation. Elaborately, the opposite of what
happens to direct variation. One increases with the other variables,
you got it, decreases. This correlations are important to consider
because you can determine and identify how two variables relates with
one another. Notice x = y (direct), y=1/x (indirect)
