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Finding the Fourth Proportional to 81.63, 122.31 and 72.47

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Solution

The fourth proportional to 81.63, 122.31 and 72.47 is: 108.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.63 : 122.31 = 72.47 : x
  2. Step 2: Convert to fraction form
    81.63/122.31 = 72.47/x
  3. Step 3: Cross multiply
    81.63x = 122.31 × 72.47
  4. Step 4: Simplify right side
    81.63x = 8,863.42
  5. Step 5: Solve for x
    x = 8,863.42/81.63
  6. Step 6: Final answer
    x = 108.58

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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.