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Finding the Fourth Proportional to 425.78, 638.33 and 391.61

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Solution

The fourth proportional to 425.78, 638.33 and 391.61 is: 587.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    425.78 : 638.33 = 391.61 : x
  2. Step 2: Convert to fraction form
    425.78/638.33 = 391.61/x
  3. Step 3: Cross multiply
    425.78x = 638.33 × 391.61
  4. Step 4: Simplify right side
    425.78x = 249,975.12
  5. Step 5: Solve for x
    x = 249,975.12/425.78
  6. Step 6: Final answer
    x = 587.10

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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.