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Finding the Fourth Proportional to 81.08, 111.90 and 72.87

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Solution

The fourth proportional to 81.08, 111.90 and 72.87 is: 100.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.08 : 111.90 = 72.87 : x
  2. Step 2: Convert to fraction form
    81.08/111.90 = 72.87/x
  3. Step 3: Cross multiply
    81.08x = 111.90 × 72.87
  4. Step 4: Simplify right side
    81.08x = 8,154.85
  5. Step 5: Solve for x
    x = 8,154.85/81.08
  6. Step 6: Final answer
    x = 100.58

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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.