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Finding the Fourth Proportional to 122.90, 169.42 and 81.38

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Solution

The fourth proportional to 122.90, 169.42 and 81.38 is: 112.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.90 : 169.42 = 81.38 : x
  2. Step 2: Convert to fraction form
    122.90/169.42 = 81.38/x
  3. Step 3: Cross multiply
    122.90x = 169.42 × 81.38
  4. Step 4: Simplify right side
    122.90x = 13,787.40
  5. Step 5: Solve for x
    x = 13,787.40/122.90
  6. Step 6: Final answer
    x = 112.18

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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.