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Finding the Fourth Proportional to 81.31, 111.79 and 72.48

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Solution

The fourth proportional to 81.31, 111.79 and 72.48 is: 99.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.31 : 111.79 = 72.48 : x
  2. Step 2: Convert to fraction form
    81.31/111.79 = 72.48/x
  3. Step 3: Cross multiply
    81.31x = 111.79 × 72.48
  4. Step 4: Simplify right side
    81.31x = 8,103.05
  5. Step 5: Solve for x
    x = 8,103.05/81.31
  6. Step 6: Final answer
    x = 99.66

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.