There are many applications in which calculus is used in real life, such as calculating minimum payments due on credit cards, determining the length of cable required to connect two substations and evaluating survey data. Just as geometry is the mathematical study of shapes, calculus is the mathematical study of change.
One of the most common ways in which calculus is used in everyday life is the calculation of monthly payments by credit card companies. When the customer's statement is processed, it is important that the minimum amount due reflects all the current variables. Calculus comes into play because the companies consider fluctuating interest rates and changing balances.
The length of cables used to connect substations has to be calculated exactly. The calculation is not as straightforward as measuring a straight line because the cable hangs from poles. This results in a curved line, and using calculus takes that change into account.
Survey data is used in a number of different applications, including developing business plans. Surveys normally are made up of a variety of questions which result in a wide range of answers. By using calculus, all of these different variables are taken into account, which results in a more precise plan of action for the company.