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Finding the Fourth Proportional to 781, 1,171.86 and 439

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Solution

The fourth proportional to 781, 1,171.86 and 439 is: 658.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    781 : 1,171.86 = 439 : x
  2. Step 2: Convert to fraction form
    781/1,171.86 = 439/x
  3. Step 3: Cross multiply
    781x = 1,171.86 × 439
  4. Step 4: Simplify right side
    781x = 514,446.54
  5. Step 5: Solve for x
    x = 514,446.54/781
  6. Step 6: Final answer
    x = 658.70

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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.