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Finding the Fourth Proportional to 81.99, 123.21 and 81.55

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Solution

The fourth proportional to 81.99, 123.21 and 81.55 is: 122.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.99 : 123.21 = 81.55 : x
  2. Step 2: Convert to fraction form
    81.99/123.21 = 81.55/x
  3. Step 3: Cross multiply
    81.99x = 123.21 × 81.55
  4. Step 4: Simplify right side
    81.99x = 10,047.78
  5. Step 5: Solve for x
    x = 10,047.78/81.99
  6. Step 6: Final answer
    x = 122.55

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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.