Nestor R. answered • 08/19/19
Mathematically-oriented professional with many years of experience
Proportions are a way to express how much of something belong to different groups.
For example, suppose a town has 5 elementary schools and a standardized test is given to all 5th graders.Let's say you want to know how many 5th graders in each school scored at or above a certain point.
There is a set number of 5th graders in each school and you know how each did on the test. Proportions, that is fractions of the 5th graders who took the test, can be calculated using an equation pi = ni / Ni, where p=proportion, n = number of 5th graders scoring at or above the target, N = number of 5th graders and the subscript i indicates the school.
The results can be put into a 2 x i table, where the 2 rows are scored at or above the target and missed the target and the columns i are the school. This allows for a visual comparison of numeric results.
A graph can be made by drawing vertical bars showing the proportions of students scoring at or above the target. The vertical axis, called Y, will have a minimum of 0, meaning no student scored at or above the target, and a maximum of 1, meaning all students scored at or above the target. The horizontal axis, called X, identifies the school. The graph gives a pictorial comparison of the results.
Together, the equation which allows calculation of proportions, the table and the graph are powerful tools that allow people to make conclusions about how well students at each school did.
