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Finding the Fourth Proportional to 421.18, 628.06 and 391.96

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Solution

The fourth proportional to 421.18, 628.06 and 391.96 is: 584.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.18 : 628.06 = 391.96 : x
  2. Step 2: Convert to fraction form
    421.18/628.06 = 391.96/x
  3. Step 3: Cross multiply
    421.18x = 628.06 × 391.96
  4. Step 4: Simplify right side
    421.18x = 246,174.40
  5. Step 5: Solve for x
    x = 246,174.40/421.18
  6. Step 6: Final answer
    x = 584.49

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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.