Dependent and Independent Variables

The input value (usually x) is called the independent variable and the output value (usually y) is called the dependent variable.

Example 1: Identify the independent and the dependent variable.

You have $1,000 saved and plan to save $50 each week. x is the number of weeks that you save and y is the total in saving. In algebraic terms, we would say that the total amount saved (y) is a function of the number of weeks (x). An equation to represent the situation would be:

y = 50x + 1000


The total amount saved (y) is dependent upon the number of weeks that you save. Therefore y is the dependent variable and x is the independent variable.

Example 2: Identify the independent and the dependent variable.

You earn a base pay of $50 and you earn $7.25 per hour. Write a function where your total earnings f(x) is a function of the number of hours (x) that you work each week.

F(x) = 7.25x + 50 * remember that f(x) is the same as y

The total earned, f(x) is dependent upon the number of hours that you work (x) therefore, f(x) is the dependent variable and x is the independent variable.

Conclusion: The independent variable is the input value (x) that is going to be multiplied by the slope (constant rate of change). The dependent variable, y or f(x), is the result obtained after entering the input value.

Related Links:
Math
algebra
Measures of Variability : Mean Absolute Deviation
Measures of Variability : Interquartile Range


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