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Proportions. Unit 5 – Math 7. Warm-Up. At Cocoa Bean Chocolate Factory, 2 pounds of their world-famous chocolate fudge sells for $1.00. Use the ratio table to find the costs of different amounts of fudge. 6. 10. 0.50. 1 .50. 2 .00. 5 .50.
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Proportions Unit 5 – Math 7
Warm-Up At Cocoa Bean Chocolate Factory, 2 pounds of their world-famous chocolate fudge sells for $1.00. Use the ratio table to find the costs of different amounts of fudge. 6 10 0.50 1.50 2.00 5.50 Adapted from MathScape: Blue “Buyer Beware” R12
What if… …We add a little more to this problem. If we had said we wanted to know how much fudge we could buy with $5.00, how many ways do we know how to solve the problem? X 10 ? X 5 ? ÷ 2 ? 10 10 0.50 ÷ 2 ? X 10 ? X 5 ? 1. Multiplication 2. Unit Rate Adapted from MathScape: Blue “Buyer Beware” R12
Any others? How about double number line diagrams? Pounds of fudge 0 2 4 6 8 10 Cost (dollars) 0 1.00 2.00 3.00 4.00 5.00 Adapted from MathScape: Blue “Buyer Beware” R12
Let’s consider something new… What are the three ways to write 2 pounds for $1.00 as a ratio? Could we use the idea of equivalent ratios to solve our problem? 2 pounds to $1.00 2 pounds : $1.00 Adapted from MathScape: Blue “Buyer Beware” R12
Equivalent Ratios How many pounds of fudge can we buy for $5.00? X 5 ? X 5 ? Adapted from MathScape: Blue “Buyer Beware” R12
Equivalent Ratios Let’s take a closer look at these ratios… When two ratios are equivalent, their cross products should be equivalent. Are they? When this is true, the two equivalent ratios are called a proportion. Adapted from MathScape: Blue “Buyer Beware” R12
To solve proportions… We can use – • Cross products • Double number lines • Ratio tables • Scale factors • Unit rates • Tape diagrams (when units of measurement are equivalent)