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Finding the Fourth Proportional to 81.87, 113.10 and 77.78

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Solution

The fourth proportional to 81.87, 113.10 and 77.78 is: 107.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.87 : 113.10 = 77.78 : x
  2. Step 2: Convert to fraction form
    81.87/113.10 = 77.78/x
  3. Step 3: Cross multiply
    81.87x = 113.10 × 77.78
  4. Step 4: Simplify right side
    81.87x = 8,796.91
  5. Step 5: Solve for x
    x = 8,796.91/81.87
  6. Step 6: Final answer
    x = 107.45

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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.