The “Rule of Three” is a mathematical method used to solve proportionality problems where three values are known, and the fourth is unknown. It involves setting up a proportion between two ratios, where one ratio contains the known values and the other contains the unknown value and one known value. For example, if 5 apples cost $2, the method can calculate the cost of 7 apples by setting up the proportion 5/2 = 7/x, where x represents the unknown cost. Online calculators designed for this purpose streamline the process, allowing users to quickly input the three known values and obtain the solution.
This technique offers a simple and efficient way to solve everyday proportionality problems, from adjusting recipe ingredients for different serving sizes to calculating discounts and exchange rates. Its historical roots can be traced back to ancient civilizations, demonstrating its enduring practicality. Its widespread use highlights its importance as a fundamental mathematical tool.
