Calculate the rate of growth of a cancerous tumor. At a certain point, the tumor will grow to the point where it is life-threatening. Doctors often use calculus in the estimation of the progression of the illness.
Estimate the space needed for packing by calculating the volume of oddly-shaped objects. Though you do not need calculus to calculate the volume of a box or ball, you most certainly will need calculus if you plan on maximizing your efficiency of packing and loading objects into tight spaces. Things like bottles, tea pots, telephones, fans and televisions are not in the form of any shapes you have learned about in algebra class. If you plan to move cross-country, it is best to determine how much space you will need before purchasing a moving truck.
Decide the best place to go base jumping. Today, with satellite imagery of almost every area of the earth available, we can obtain a 3D map of a mountainous area. After modeling this map mathematically as a three-dimensional object, you can use derivatives to find the point at which there is the steepest drop-off. In this way, differential equations can essentially tell you the idea place for a base jump in that area.
Analyze investment plans. With many investment options, you may have difficulty deciding which one is most suitable for you. The answer lies in using calculus to calculate the rates of growth of various options. Understanding how to take the derivative of exponents and functions of compound interest will allow you to know which options offer the best value. If you want to take it even further, you could study stochastic calculus to better understand more complicated forms of investment, like stocks, options and mutual funds.
Determine the extinction of a species. By collecting data on a species of animals that is preyed on by another, you can then enter this data into a predator-prey equation. Such equations allow you to calculate the population growth and decline of interdependent animals. Naturalists use such methods to determine which species are endangered.