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Finding the Fourth Proportional to 428.20, 641.67 and 254.91

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Solution

The fourth proportional to 428.20, 641.67 and 254.91 is: 381.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.20 : 641.67 = 254.91 : x
  2. Step 2: Convert to fraction form
    428.20/641.67 = 254.91/x
  3. Step 3: Cross multiply
    428.20x = 641.67 × 254.91
  4. Step 4: Simplify right side
    428.20x = 163,568.10
  5. Step 5: Solve for x
    x = 163,568.10/428.20
  6. Step 6: Final answer
    x = 381.99

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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.