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Finding the Fourth Proportional to 686.88, 1,029.90 and 321.78

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Solution

The fourth proportional to 686.88, 1,029.90 and 321.78 is: 482.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.88 : 1,029.90 = 321.78 : x
  2. Step 2: Convert to fraction form
    686.88/1,029.90 = 321.78/x
  3. Step 3: Cross multiply
    686.88x = 1,029.90 × 321.78
  4. Step 4: Simplify right side
    686.88x = 331,401.22
  5. Step 5: Solve for x
    x = 331,401.22/686.88
  6. Step 6: Final answer
    x = 482.47

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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.