How to Solve Problems Using Cross Multiplication
Description
This video gives an example of how to solve proportions using the cross-multiplication technique. Several examples are provided as well as easy to follow step-by-step instructions. This video also provides sample word problems, with examples of how to use the cross-multiplication technique with word problems.
Overview
Cross multiplication is often used with fractions and proportions, and is found in many word problems. A cross multiplication problem will normally have two fractions set equal to each other, with one fraction complete, and one fraction with one variable in either the numerator or the denominator. Take the numerator of the first fraction and multiply it by the denominator, then set it equal to the denominator of the first fraction multiplied by the numerator of the second fraction. An example is x / y = a / b. You would change this to x * b = y * a. From there you can simply solve for the variable.
