Use cross products to demonstrate whether or not the two ratios are equivalent: 4/6 and 14/21.

Question

Please help, this question is from my study guide for a big test coming up. Thank you!! 

Answer 1

Hi Kaitlyn, if I have a/b and c/d, and I want to find out if they are equivalent all I have to do is:

 

a/b = c/d

 

multiply a * d and b * c, or cross multiply. If the number are equal, the ratios of equivalent.

 

4/6 = 14/21

 

4 * 21 = 6 * 14, or 84 = 84, the ratios are equivalent.

 

A simpler way is to reduce all fractions to lowest terms and compare them:

 

4/6 can be reduced to 2/3

 

14/21 can be reduced to 2/3

 

The ratios are equivalent.

 

Questions?