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Finding the Fourth Proportional to 814.20, 1,221.70 and 381.28

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Solution

The fourth proportional to 814.20, 1,221.70 and 381.28 is: 572.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    814.20 : 1,221.70 = 381.28 : x
  2. Step 2: Convert to fraction form
    814.20/1,221.70 = 381.28/x
  3. Step 3: Cross multiply
    814.20x = 1,221.70 × 381.28
  4. Step 4: Simplify right side
    814.20x = 465,809.78
  5. Step 5: Solve for x
    x = 465,809.78/814.20
  6. Step 6: Final answer
    x = 572.11

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.