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Finding the Fourth Proportional to 781.14, 1,171.55 and 287.85

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Solution

The fourth proportional to 781.14, 1,171.55 and 287.85 is: 431.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.14 : 1,171.55 = 287.85 : x
  2. Step 2: Convert to fraction form
    781.14/1,171.55 = 287.85/x
  3. Step 3: Cross multiply
    781.14x = 1,171.55 × 287.85
  4. Step 4: Simplify right side
    781.14x = 337,231.39
  5. Step 5: Solve for x
    x = 337,231.39/781.14
  6. Step 6: Final answer
    x = 431.72

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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.