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Finding the Fourth Proportional to 81.06, 120.91 and 68.90

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Solution

The fourth proportional to 81.06, 120.91 and 68.90 is: 102.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.06 : 120.91 = 68.90 : x
  2. Step 2: Convert to fraction form
    81.06/120.91 = 68.90/x
  3. Step 3: Cross multiply
    81.06x = 120.91 × 68.90
  4. Step 4: Simplify right side
    81.06x = 8,330.35
  5. Step 5: Solve for x
    x = 8,330.35/81.06
  6. Step 6: Final answer
    x = 102.77

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.