How To: Use cross products to solve proportions

Use cross products to solve proportions

To solve a proportion for a variable you should employ cross multiplication. The basis of cross multiplication is the property which states that the product of the numerator of one fraction and the denominator of what it is set equal to is equal to the product of the remaining denominator and numerator. For example if you have x/15=21/45 you simply need to multiply x by 45 and 15 by 21 then set them equal to each other. The result of this is 45x=315. To solve this new problem for x, divide both sides by 45. The final result of this is x=7. This skill is important for many word and trigonometry problems.

Want to master Microsoft Excel and take your work-from-home job prospects to the next level? Jump-start your career with our Premium A-to-Z Microsoft Excel Training Bundle from the new Gadget Hacks Shop and get lifetime access to more than 40 hours of Basic to Advanced instruction on functions, formula, tools, and more.

Buy Now (97% off) >

Our Best Phone Hacks

Gadget Hacks' tips — delivered daily.

Be the First to Comment

Share Your Thoughts

  • Hot
  • Latest