Definition
Dependent variable
In a quantity relationship, the dependent variable is the output that changes according to the input.
What it means
Start with the input, then use the rule. The value that comes out is the dependent variable because it follows the input. In c = 4h, the cost c changes when the number of hours h changes.
Remember it
Input first; the dependent value follows the rule.
Example
A bicycle costs 4 dollars to rent for each hour. Let h be hours and c be total cost, so c = 4h. If h = 3, then c = 12. The cost c is the dependent variable.
Watch for
A variable is not dependent just because it is written on the left or drawn on the vertical axis; the problem's stated relationship gives it that role.
Common mix-up
Dependent describes a mathematical role, not proof that one quantity causes the other.
Exact meaning
The dependent variable names the output quantity in a stated relationship. Once the independent variable's input value is chosen or given, the relationship determines this output value.