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Finding the Fourth Proportional to 521.11, 781.77 and 261.28

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Solution

The fourth proportional to 521.11, 781.77 and 261.28 is: 391.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    521.11 : 781.77 = 261.28 : x
  2. Step 2: Convert to fraction form
    521.11/781.77 = 261.28/x
  3. Step 3: Cross multiply
    521.11x = 781.77 × 261.28
  4. Step 4: Simplify right side
    521.11x = 204,260.87
  5. Step 5: Solve for x
    x = 204,260.87/521.11
  6. Step 6: Final answer
    x = 391.97

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.