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Finding the Fourth Proportional to 619.78, 855 and 398.62

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Solution

The fourth proportional to 619.78, 855 and 398.62 is: 549.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    619.78 : 855 = 398.62 : x
  2. Step 2: Convert to fraction form
    619.78/855 = 398.62/x
  3. Step 3: Cross multiply
    619.78x = 855 × 398.62
  4. Step 4: Simplify right side
    619.78x = 340,820.10
  5. Step 5: Solve for x
    x = 340,820.10/619.78
  6. Step 6: Final answer
    x = 549.90

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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.