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Finding the Fourth Proportional to 619.62, 855.22 and 420.78

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Solution

The fourth proportional to 619.62, 855.22 and 420.78 is: 580.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    619.62 : 855.22 = 420.78 : x
  2. Step 2: Convert to fraction form
    619.62/855.22 = 420.78/x
  3. Step 3: Cross multiply
    619.62x = 855.22 × 420.78
  4. Step 4: Simplify right side
    619.62x = 359,857.31
  5. Step 5: Solve for x
    x = 359,857.31/619.62
  6. Step 6: Final answer
    x = 580.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.