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Finding the Fourth Proportional to 81.74, 122.61 and 71.78

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Solution

The fourth proportional to 81.74, 122.61 and 71.78 is: 107.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.74 : 122.61 = 71.78 : x
  2. Step 2: Convert to fraction form
    81.74/122.61 = 71.78/x
  3. Step 3: Cross multiply
    81.74x = 122.61 × 71.78
  4. Step 4: Simplify right side
    81.74x = 8,800.95
  5. Step 5: Solve for x
    x = 8,800.95/81.74
  6. Step 6: Final answer
    x = 107.67

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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.