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Finding the Fourth Proportional to 257.28, 385.92 and 129.12

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Solution

The fourth proportional to 257.28, 385.92 and 129.12 is: 193.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.28 : 385.92 = 129.12 : x
  2. Step 2: Convert to fraction form
    257.28/385.92 = 129.12/x
  3. Step 3: Cross multiply
    257.28x = 385.92 × 129.12
  4. Step 4: Simplify right side
    257.28x = 49,829.99
  5. Step 5: Solve for x
    x = 49,829.99/257.28
  6. Step 6: Final answer
    x = 193.68

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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.