For functions in context, the input is often referred to as the independent variable because it can be chosen arbitrarily from the domain. Conversely, the output is called the dependent variable, because its value depends on the value of the independent variable. For example, consider how the cost of fruit is determined by weight. $$\begin{array}{ccccc}\text{cost}& =& \text{unit price }& \times & \text{ weight}\\ y& =& 2.5& \cdot & x\end{array}$$ If the unit price of clementines is $\$2.50/\text{lb},$ then the total cost of buying clementines depends on how many pounds are bought. Therefore, the cost $y$ of clementines is the dependent variable and the number of pounds $x$ is the independent variable.