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Finding the Fourth Proportional to 781.09, 1,077.89 and 431.78

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Solution

The fourth proportional to 781.09, 1,077.89 and 431.78 is: 595.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.09 : 1,077.89 = 431.78 : x
  2. Step 2: Convert to fraction form
    781.09/1,077.89 = 431.78/x
  3. Step 3: Cross multiply
    781.09x = 1,077.89 × 431.78
  4. Step 4: Simplify right side
    781.09x = 465,405.95
  5. Step 5: Solve for x
    x = 465,405.95/781.09
  6. Step 6: Final answer
    x = 595.85

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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.