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Finding the Fourth Proportional to 81.31, 122.07 and 61.15

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Solution

The fourth proportional to 81.31, 122.07 and 61.15 is: 91.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.31 : 122.07 = 61.15 : x
  2. Step 2: Convert to fraction form
    81.31/122.07 = 61.15/x
  3. Step 3: Cross multiply
    81.31x = 122.07 × 61.15
  4. Step 4: Simplify right side
    81.31x = 7,464.58
  5. Step 5: Solve for x
    x = 7,464.58/81.31
  6. Step 6: Final answer
    x = 91.80

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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.