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Finding the Fourth Proportional to 812.28, 1,218.74 and 721.68

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Solution

The fourth proportional to 812.28, 1,218.74 and 721.68 is: 1,082.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.28 : 1,218.74 = 721.68 : x
  2. Step 2: Convert to fraction form
    812.28/1,218.74 = 721.68/x
  3. Step 3: Cross multiply
    812.28x = 1,218.74 × 721.68
  4. Step 4: Simplify right side
    812.28x = 879,540.28
  5. Step 5: Solve for x
    x = 879,540.28/812.28
  6. Step 6: Final answer
    x = 1,082.80

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.