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Finding the Fourth Proportional to 709.78, 979.45 and 399.22

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Solution

The fourth proportional to 709.78, 979.45 and 399.22 is: 550.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.78 : 979.45 = 399.22 : x
  2. Step 2: Convert to fraction form
    709.78/979.45 = 399.22/x
  3. Step 3: Cross multiply
    709.78x = 979.45 × 399.22
  4. Step 4: Simplify right side
    709.78x = 391,016.03
  5. Step 5: Solve for x
    x = 391,016.03/709.78
  6. Step 6: Final answer
    x = 550.90

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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.