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Finding the Fourth Proportional to 122.66, 169.14 and 81.21

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Solution

The fourth proportional to 122.66, 169.14 and 81.21 is: 111.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.66 : 169.14 = 81.21 : x
  2. Step 2: Convert to fraction form
    122.66/169.14 = 81.21/x
  3. Step 3: Cross multiply
    122.66x = 169.14 × 81.21
  4. Step 4: Simplify right side
    122.66x = 13,735.86
  5. Step 5: Solve for x
    x = 13,735.86/122.66
  6. Step 6: Final answer
    x = 111.99

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.