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Finding the Fourth Proportional to 81.69, 123 and 71.67

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Solution

The fourth proportional to 81.69, 123 and 71.67 is: 107.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.69 : 123 = 71.67 : x
  2. Step 2: Convert to fraction form
    81.69/123 = 71.67/x
  3. Step 3: Cross multiply
    81.69x = 123 × 71.67
  4. Step 4: Simplify right side
    81.69x = 8,815.41
  5. Step 5: Solve for x
    x = 8,815.41/81.69
  6. Step 6: Final answer
    x = 107.91

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.