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Finding the Fourth Proportional to 81.86, 112.14 and 78.77

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Solution

The fourth proportional to 81.86, 112.14 and 78.77 is: 107.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.86 : 112.14 = 78.77 : x
  2. Step 2: Convert to fraction form
    81.86/112.14 = 78.77/x
  3. Step 3: Cross multiply
    81.86x = 112.14 × 78.77
  4. Step 4: Simplify right side
    81.86x = 8,833.55
  5. Step 5: Solve for x
    x = 8,833.55/81.86
  6. Step 6: Final answer
    x = 107.92

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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.