1. That’s Not Fair!!!
Or, Proportions

2. Is it fair?
Basically, proportions tell us if rates or ratios are equal, fair
Rate example: One day in gym you have to run 2 laps in 5 minutes. The next day you have to run 3 laps in 7 minutes. Are the rates for the 2 days equal?
Ratio example: One day your mom says your brother can have 3 mini cookies for every 2 scoops of vegetables he eats. The next day she says you can have 4 mini cookies for every 3 scoops of vegetables you eat. Is this ratio between you and your brother fair?

3. Give it a try
Do 6/4 and 8/12 make a proportion? In other words, are these fractions proportional?
Compare them in simplest form: 6/4 = 3/2 and 8/12 = 2/3
3/2 is NOT proportional with 2/3; the two fractions do NOT make a proportion

4. One more time Compare each ratio X to Y in simplest form.
1/2 1
3/2 2 Y 3 6 9 12
Compare each ratio X to Y in simplest form.
½ / 3 = 1/6 1 / 6 = 1/6 3/2 / 9 = 1/6 2 / 12 = 1/6
The ratios ARE equivalent

5. Do these ratios form a proportion?
1/2 and 5/10 YES
4/6 and 18/24 NO
10/3 and 5/6 NO
25/20 and 15/12 YES

6. Cross Products Pretend A/B represents 2/3 and C/D represents 6/9
2/3 = 6/9
A/B = C/D
2 x 9 =18
3 x 6 = 18
AD = BC
Cross Products = the products of AD and BC
Cross Products Property = the cross products of a proportion are equal
Psst…this is a SHORT CUT to find out if ratios are equal

7. Suggested Practice
7.5.2 Proportions Pg