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Finding the Fourth Proportional to 421.38, 628.61 and 391.92

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Solution

The fourth proportional to 421.38, 628.61 and 391.92 is: 584.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.38 : 628.61 = 391.92 : x
  2. Step 2: Convert to fraction form
    421.38/628.61 = 391.92/x
  3. Step 3: Cross multiply
    421.38x = 628.61 × 391.92
  4. Step 4: Simplify right side
    421.38x = 246,365.81
  5. Step 5: Solve for x
    x = 246,365.81/421.38
  6. Step 6: Final answer
    x = 584.66

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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.