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Finding the Fourth Proportional to 81.07, 120.92 and 70.85

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Solution

The fourth proportional to 81.07, 120.92 and 70.85 is: 105.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.07 : 120.92 = 70.85 : x
  2. Step 2: Convert to fraction form
    81.07/120.92 = 70.85/x
  3. Step 3: Cross multiply
    81.07x = 120.92 × 70.85
  4. Step 4: Simplify right side
    81.07x = 8,567.13
  5. Step 5: Solve for x
    x = 8,567.13/81.07
  6. Step 6: Final answer
    x = 105.68

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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.