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Finding the Fourth Proportional to 81.72, 122.42 and 68.96

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Solution

The fourth proportional to 81.72, 122.42 and 68.96 is: 103.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.72 : 122.42 = 68.96 : x
  2. Step 2: Convert to fraction form
    81.72/122.42 = 68.96/x
  3. Step 3: Cross multiply
    81.72x = 122.42 × 68.96
  4. Step 4: Simplify right side
    81.72x = 8,442.08
  5. Step 5: Solve for x
    x = 8,442.08/81.72
  6. Step 6: Final answer
    x = 103.30

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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.