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Finding the Fourth Proportional to 489.87, 676.89 and 392.40

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Solution

The fourth proportional to 489.87, 676.89 and 392.40 is: 542.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.87 : 676.89 = 392.40 : x
  2. Step 2: Convert to fraction form
    489.87/676.89 = 392.40/x
  3. Step 3: Cross multiply
    489.87x = 676.89 × 392.40
  4. Step 4: Simplify right side
    489.87x = 265,611.64
  5. Step 5: Solve for x
    x = 265,611.64/489.87
  6. Step 6: Final answer
    x = 542.21

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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.