A 421-inch candle burns down in 9 hours. Assuming the candles are the same thickness and make (that is, directly proportional), how long would it take a 3 -inch candle to burn down?
Q. A 421-inch candle burns down in 9 hours. Assuming the candles are the same thickness and make (that is, directly proportional), how long would it take a 3 -inch candle to burn down?
Set Proportion: We know:● Time taken for a 4.5-inch candle to burn down: 9 hours● Time taken for a 3-inch candle to burn down: x hoursChoose a proportion that represents the problem.4.5 inches9 hours=3 inchesx hours
Cross-Multiply: We have: 4.59=3xSelect the equation rewritten after cross-multiplying.The two cross products:9×3 and 4.5×xSo the equation becomes 9×3=4.5×x
Simplify Equation: We have: 9×3=4.5×xSelect the equation we get after simplifying both sides.9×3=4.5×x27=4.5x
Solve for x:27=4.5xSolve for x.27=4.5x4.527=4.5(4.5x)6=xIt would take 6 hours for a 3-inch candle to burn down.
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