2.3 Proportional Reasoning
A proportion is a relationship that says that two ratios or two rates are equal.
A rate/ratio problem can be solved using proportional reasoning
 Using a unit rate
 Using a proportion
 Electricity costs 11.58 cents for 3 kWh. How much does 18 kWh cost?
Using a unit rate:
Using a proportion:
• There are 42 players on 7 volleyball teams. How many players are on 4 teams?
Using a unit rate:
Using a proportion:
• True or False?
-If there are 60 mL of sugar in 600 mL of pop,
then 1 L of pop contains 100 mL of sugar.
-A car needs 9.4 L of gasoline to go 100 km.
It will need 56.4 L to go 600 km
• If 15 oranges cost $2.25, then how much does it cost to buy 20 oranges?
Ratio Page 1
• If 15 oranges cost $2.25, then how much does it cost to buy 20 oranges?
Using Cross-Multiplication to solve proportions.
• A 24 m tree casts a 42 m shadow. How tall is a building with a 147 m shadow?
• On a map 2.5 cm represents 400 km. What distance would a 3.8 cm line represent?
Assignment: p67 #6,9,10,12,14,17-23,28
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