A speedometer is a measuring instrument. What are the independent and dependent variables when it is used? Give an example of an extraneous variable for this measurement. Solution Input time is the independent variable where as out put mileage is the dependent variable. Mileage is a function which takes something as input that cant be controlled by us. Example for this is robotic speedometer. It is clear that the dependent variables are derived from independent variables. Here time is independent variable, the dependent variables can be extended to derivatives such as velocity,acceleration,etc..