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Example: The circumference of a circle with a diameter of 4 meters is about 12.56 meters. A circle's circumference is proportional to its diameter. Write an equation relating the circumference of a circle to its diameter. What would be the circumference of a circle with a 5inch diameter? The constant of proportionality between circumference and diameter 12.56/4 = 3.14 The circumference is about 3.14 times the diameter. Let C = circumference and d = diameter. C = 3.14d = 3.14(5) = 15.7 The circumference is about 15.7 inches Directions: Choose the correct answer. Also write at least 5 examples of your own. 