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Finding the Fourth Proportional to 686.60, 1,029.06 and 426.20

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Solution

The fourth proportional to 686.60, 1,029.06 and 426.20 is: 638.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.60 : 1,029.06 = 426.20 : x
  2. Step 2: Convert to fraction form
    686.60/1,029.06 = 426.20/x
  3. Step 3: Cross multiply
    686.60x = 1,029.06 × 426.20
  4. Step 4: Simplify right side
    686.60x = 438,585.37
  5. Step 5: Solve for x
    x = 438,585.37/686.60
  6. Step 6: Final answer
    x = 638.78

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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.