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Finding the Fourth Proportional to 81.70, 122.94 and 76.84

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Solution

The fourth proportional to 81.70, 122.94 and 76.84 is: 115.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.70 : 122.94 = 76.84 : x
  2. Step 2: Convert to fraction form
    81.70/122.94 = 76.84/x
  3. Step 3: Cross multiply
    81.70x = 122.94 × 76.84
  4. Step 4: Simplify right side
    81.70x = 9,446.71
  5. Step 5: Solve for x
    x = 9,446.71/81.70
  6. Step 6: Final answer
    x = 115.63

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.