A 321-inch candle burns down in 7 hours. Assuming the candles are the same thickness and make (that is, directly proportional), how long would it take a 421-inch candle to burn down?Answer: hours
Q. A 321-inch candle burns down in 7 hours. Assuming the candles are the same thickness and make (that is, directly proportional), how long would it take a 421-inch candle to burn down?Answer: hours
Establish Relationship: Establish the relationship between the length of the candle and the time it takes to burn down.We know:● Time taken for a 3(21)-inch candle to burn down: 7 hours● Time taken for a 4(21)-inch candle to burn down: x hoursSet up a proportion to represent the problem.7 hours3.5 inches=x hours4.5 inches
Set Up Proportion: Cross-multiply to find the relationship between the lengths of the candles and the time it takes to burn down.The two cross products are:3.5×x and 7×4.5So the equation becomes 3.5×x=7×4.5
Cross-Multiply: Calculate the cross product on the right side of the equation.7×4.5=31.5So the equation now is 3.5×x=31.5
Calculate Cross Product: Solve for x by dividing both sides of the equation by 3.5.3.5×x=31.5x=3.531.5x=9
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