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Finding the Fourth Proportional to 518.87, 778.28 and 128.86

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Solution

The fourth proportional to 518.87, 778.28 and 128.86 is: 193.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    518.87 : 778.28 = 128.86 : x
  2. Step 2: Convert to fraction form
    518.87/778.28 = 128.86/x
  3. Step 3: Cross multiply
    518.87x = 778.28 × 128.86
  4. Step 4: Simplify right side
    518.87x = 100,286.57
  5. Step 5: Solve for x
    x = 100,286.57/518.87
  6. Step 6: Final answer
    x = 193.28

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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.