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Finding the Fourth Proportional to 81.87, 112.49 and 78.29

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Solution

The fourth proportional to 81.87, 112.49 and 78.29 is: 107.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.87 : 112.49 = 78.29 : x
  2. Step 2: Convert to fraction form
    81.87/112.49 = 78.29/x
  3. Step 3: Cross multiply
    81.87x = 112.49 × 78.29
  4. Step 4: Simplify right side
    81.87x = 8,806.73
  5. Step 5: Solve for x
    x = 8,806.73/81.87
  6. Step 6: Final answer
    x = 107.57

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.