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Finding the Fourth Proportional to 428.21, 638.54 and 394.55

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Solution

The fourth proportional to 428.21, 638.54 and 394.55 is: 588.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.21 : 638.54 = 394.55 : x
  2. Step 2: Convert to fraction form
    428.21/638.54 = 394.55/x
  3. Step 3: Cross multiply
    428.21x = 638.54 × 394.55
  4. Step 4: Simplify right side
    428.21x = 251,930.79
  5. Step 5: Solve for x
    x = 251,930.79/428.21
  6. Step 6: Final answer
    x = 588.34

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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.