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Finding the Fourth Proportional to 425.76, 639.20 and 412

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Solution

The fourth proportional to 425.76, 639.20 and 412 is: 618.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    425.76 : 639.20 = 412 : x
  2. Step 2: Convert to fraction form
    425.76/639.20 = 412/x
  3. Step 3: Cross multiply
    425.76x = 639.20 × 412
  4. Step 4: Simplify right side
    425.76x = 263,350.40
  5. Step 5: Solve for x
    x = 263,350.40/425.76
  6. Step 6: Final answer
    x = 618.54

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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.