1. Complete the pattern… 1 =2=3=4=5= 6=7=8=9=10=

2. Proportionality If two quantities change by a related amount they are said to be in proportion or PROPORTIONALto each other. The symbol that indicates proportionality is

3. Direct Proportionality 4 is a relationship between quantities such that when one increases the other increases in the same ratio or when one quantity decreases the other decreases in the same ratio.

4. Constant of Proportionality 4 When quantity a is directly proportional to quantity b, this is written as a b. the fixed relationship between the quantities is called the constant of proportionality and the relationship can also be written as a = kb.

5. EXAMPLE IF ONE WATERMELON FEEDS 8 PEOPLE, THE RATIO OF MELONS TO PEOPLE IS 1 : 8 HOW MANY WATERMELONS WOULD FEED 16 PEOPLE? HOW MANY WATERMELONS WOULD BE NEEDED TO FEED 4 PEOPLE? THE NUMBER OF PEOPLE FED IS IN DIRECT PROPORTION TO THE NUMBER OF WATERMELONS. THE RATIO OF PEOPLE (QUANTITY A) TO WATERMELONS (QUANTITY B) IS 8 : 1, SO THE CONSTANT OF PROPORTIONALITY IS 8. THIS MEANS THAT THE NUMBER OF PEOPLE THAT CAN BE FED IS ALWAYS 8 TIMES THE NUMBER OF MELONS.

6. A GRAPH IS A GOOD WAY TO HELP VISUALISE DIRECT PROPORTION

7. SET A 3 6 4 8 12 24 SET B 3 9 4 10 12 18 SET C 10 5 12 6 SET D 12 18 4 6 4 For the following sets of numbers: –Are the values directly proportional? –If so, find the constant of proportionality.