+ Proportion n An equation that shows two ratios are equivalent n There are two ways to determine if two ratios form a proportion n 1. Cross-Products Rule n 2. Fractions

+ Cross Product Rule n Two Ratios form a proportion if their cross products are equal n Cross Multiply 2 = 6 2 x 9 = 3 x 16 18 = 18 It’s a proportion 3 9

+ Cross Product Rule n Use the cross product rule to see if the following ratios are proportions n 1/5 = 6/10 n ¾ = 7/5 n 2/1=10/5 n 6/10 = 18/30 n 7/4=14/18 n 6/60= 10/90 n 7/5= 49/35 n 8/5= 40/50

+ Fractions n 2 Simplify both ratios and the value should be equivalent and if the values are the same the ratio is equivalent = 6 1 3 3 9 = 1 3 The above ratios are a proportion!

+ Fraction Rule n 6/12= 8/16 n 4/6=8/10 n 10/15= 15/30 n 24/28= 2/4 n 12/36= 3/9

+ Find the missing number n To find the missing number in a proportion you may use either one of the rules we discussed (cross product or fraction) n Remember the ratios must always be equal! 4 2 4 n= 28 n=7 = 14 4 n 2 = 14 n n=7

+ Find the Missing Number n 5/1= 15/n n 12/21 = n/7 n 15/8 = n/36 n ¾ =6/8 n 9/10 = 81 /n n n/1 = 14/7 n 32/36 = 8/n

+ Find N n n/12 = 5/20 n/7 = 6/2 n n/10= 3/5 18/28=n/8 n n/3 = 7/21 n 6/5 = 24/n n 4/n= 16/36 n 2/n = 14/ 28 n 12/4 = 18/n n 5/15= n/12 n n/16= 3/6 n n/9= 5/9