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Finding the Fourth Proportional to 421.92, 629.76 and 391.88

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Solution

The fourth proportional to 421.92, 629.76 and 391.88 is: 584.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.92 : 629.76 = 391.88 : x
  2. Step 2: Convert to fraction form
    421.92/629.76 = 391.88/x
  3. Step 3: Cross multiply
    421.92x = 629.76 × 391.88
  4. Step 4: Simplify right side
    421.92x = 246,787.20
  5. Step 5: Solve for x
    x = 246,787.20/421.92
  6. Step 6: Final answer
    x = 584.91

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.