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Finding the Fourth Proportional to 489.92, 676.78 and 391.56

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Solution

The fourth proportional to 489.92, 676.78 and 391.56 is: 540.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.92 : 676.78 = 391.56 : x
  2. Step 2: Convert to fraction form
    489.92/676.78 = 391.56/x
  3. Step 3: Cross multiply
    489.92x = 676.78 × 391.56
  4. Step 4: Simplify right side
    489.92x = 264,999.98
  5. Step 5: Solve for x
    x = 264,999.98/489.92
  6. Step 6: Final answer
    x = 540.90

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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.