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Finding the Fourth Proportional to 686.10, 1,029.15 and 426.90

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Solution

The fourth proportional to 686.10, 1,029.15 and 426.90 is: 640.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.10 : 1,029.15 = 426.90 : x
  2. Step 2: Convert to fraction form
    686.10/1,029.15 = 426.90/x
  3. Step 3: Cross multiply
    686.10x = 1,029.15 × 426.90
  4. Step 4: Simplify right side
    686.10x = 439,344.14
  5. Step 5: Solve for x
    x = 439,344.14/686.10
  6. Step 6: Final answer
    x = 640.35

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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.