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Finding the Fourth Proportional to 680.92, 1,021.56 and 391.72

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Solution

The fourth proportional to 680.92, 1,021.56 and 391.72 is: 587.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.92 : 1,021.56 = 391.72 : x
  2. Step 2: Convert to fraction form
    680.92/1,021.56 = 391.72/x
  3. Step 3: Cross multiply
    680.92x = 1,021.56 × 391.72
  4. Step 4: Simplify right side
    680.92x = 400,165.48
  5. Step 5: Solve for x
    x = 400,165.48/680.92
  6. Step 6: Final answer
    x = 587.68

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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.