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Finding the Fourth Proportional to 686.34, 1,029.78 and 378.54

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Solution

The fourth proportional to 686.34, 1,029.78 and 378.54 is: 567.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.34 : 1,029.78 = 378.54 : x
  2. Step 2: Convert to fraction form
    686.34/1,029.78 = 378.54/x
  3. Step 3: Cross multiply
    686.34x = 1,029.78 × 378.54
  4. Step 4: Simplify right side
    686.34x = 389,812.92
  5. Step 5: Solve for x
    x = 389,812.92/686.34
  6. Step 6: Final answer
    x = 567.96

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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.