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Finding the Fourth Proportional to 81.83, 121.82 and 77.90

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Solution

The fourth proportional to 81.83, 121.82 and 77.90 is: 115.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.83 : 121.82 = 77.90 : x
  2. Step 2: Convert to fraction form
    81.83/121.82 = 77.90/x
  3. Step 3: Cross multiply
    81.83x = 121.82 × 77.90
  4. Step 4: Simplify right side
    81.83x = 9,489.39
  5. Step 5: Solve for x
    x = 9,489.39/81.83
  6. Step 6: Final answer
    x = 115.96

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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.