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Finding the Fourth Proportional to 391.92, 587.84 and 128.38

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Solution

The fourth proportional to 391.92, 587.84 and 128.38 is: 192.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.92 : 587.84 = 128.38 : x
  2. Step 2: Convert to fraction form
    391.92/587.84 = 128.38/x
  3. Step 3: Cross multiply
    391.92x = 587.84 × 128.38
  4. Step 4: Simplify right side
    391.92x = 75,466.90
  5. Step 5: Solve for x
    x = 75,466.90/391.92
  6. Step 6: Final answer
    x = 192.56

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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.