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Finding the Fourth Proportional to 619.40, 855.35 and 398.74

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Solution

The fourth proportional to 619.40, 855.35 and 398.74 is: 550.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    619.40 : 855.35 = 398.74 : x
  2. Step 2: Convert to fraction form
    619.40/855.35 = 398.74/x
  3. Step 3: Cross multiply
    619.40x = 855.35 × 398.74
  4. Step 4: Simplify right side
    619.40x = 341,062.26
  5. Step 5: Solve for x
    x = 341,062.26/619.40
  6. Step 6: Final answer
    x = 550.63

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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.