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Finding the Fourth Proportional to 624.78, 861.30 and 391.50

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Solution

The fourth proportional to 624.78, 861.30 and 391.50 is: 539.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    624.78 : 861.30 = 391.50 : x
  2. Step 2: Convert to fraction form
    624.78/861.30 = 391.50/x
  3. Step 3: Cross multiply
    624.78x = 861.30 × 391.50
  4. Step 4: Simplify right side
    624.78x = 337,198.95
  5. Step 5: Solve for x
    x = 337,198.95/624.78
  6. Step 6: Final answer
    x = 539.71

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.