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Finding the Fourth Proportional to 122.31, 168.78 and 69.85

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Solution

The fourth proportional to 122.31, 168.78 and 69.85 is: 96.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.31 : 168.78 = 69.85 : x
  2. Step 2: Convert to fraction form
    122.31/168.78 = 69.85/x
  3. Step 3: Cross multiply
    122.31x = 168.78 × 69.85
  4. Step 4: Simplify right side
    122.31x = 11,789.28
  5. Step 5: Solve for x
    x = 11,789.28/122.31
  6. Step 6: Final answer
    x = 96.39

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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.