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Finding the Fourth Proportional to 81.87, 122.94 and 81.24

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Solution

The fourth proportional to 81.87, 122.94 and 81.24 is: 121.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.87 : 122.94 = 81.24 : x
  2. Step 2: Convert to fraction form
    81.87/122.94 = 81.24/x
  3. Step 3: Cross multiply
    81.87x = 122.94 × 81.24
  4. Step 4: Simplify right side
    81.87x = 9,987.65
  5. Step 5: Solve for x
    x = 9,987.65/81.87
  6. Step 6: Final answer
    x = 121.99

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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.