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Finding the Fourth Proportional to 686.52, 1,029.78 and 321.42

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Solution

The fourth proportional to 686.52, 1,029.78 and 321.42 is: 482.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.52 : 1,029.78 = 321.42 : x
  2. Step 2: Convert to fraction form
    686.52/1,029.78 = 321.42/x
  3. Step 3: Cross multiply
    686.52x = 1,029.78 × 321.42
  4. Step 4: Simplify right side
    686.52x = 330,991.89
  5. Step 5: Solve for x
    x = 330,991.89/686.52
  6. Step 6: Final answer
    x = 482.13

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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.