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Finding the Fourth Proportional to 619.84, 855.21 and 399.09

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Solution

The fourth proportional to 619.84, 855.21 and 399.09 is: 550.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    619.84 : 855.21 = 399.09 : x
  2. Step 2: Convert to fraction form
    619.84/855.21 = 399.09/x
  3. Step 3: Cross multiply
    619.84x = 855.21 × 399.09
  4. Step 4: Simplify right side
    619.84x = 341,305.76
  5. Step 5: Solve for x
    x = 341,305.76/619.84
  6. Step 6: Final answer
    x = 550.64

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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.