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Finding the Fourth Proportional to 619.90, 855.35 and 398.80

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Solution

The fourth proportional to 619.90, 855.35 and 398.80 is: 550.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    619.90 : 855.35 = 398.80 : x
  2. Step 2: Convert to fraction form
    619.90/855.35 = 398.80/x
  3. Step 3: Cross multiply
    619.90x = 855.35 × 398.80
  4. Step 4: Simplify right side
    619.90x = 341,113.58
  5. Step 5: Solve for x
    x = 341,113.58/619.90
  6. Step 6: Final answer
    x = 550.27

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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.