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Finding the Fourth Proportional to 428.08, 638.66 and 381.91

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Solution

The fourth proportional to 428.08, 638.66 and 381.91 is: 569.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.08 : 638.66 = 381.91 : x
  2. Step 2: Convert to fraction form
    428.08/638.66 = 381.91/x
  3. Step 3: Cross multiply
    428.08x = 638.66 × 381.91
  4. Step 4: Simplify right side
    428.08x = 243,910.64
  5. Step 5: Solve for x
    x = 243,910.64/428.08
  6. Step 6: Final answer
    x = 569.78

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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.