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Finding the Fourth Proportional to 421.28, 628.42 and 391.58

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Solution

The fourth proportional to 421.28, 628.42 and 391.58 is: 584.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.28 : 628.42 = 391.58 : x
  2. Step 2: Convert to fraction form
    421.28/628.42 = 391.58/x
  3. Step 3: Cross multiply
    421.28x = 628.42 × 391.58
  4. Step 4: Simplify right side
    421.28x = 246,076.70
  5. Step 5: Solve for x
    x = 246,076.70/421.28
  6. Step 6: Final answer
    x = 584.12

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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.