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Finding the Fourth Proportional to 81.10, 111.96 and 76.87

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Solution

The fourth proportional to 81.10, 111.96 and 76.87 is: 106.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.10 : 111.96 = 76.87 : x
  2. Step 2: Convert to fraction form
    81.10/111.96 = 76.87/x
  3. Step 3: Cross multiply
    81.10x = 111.96 × 76.87
  4. Step 4: Simplify right side
    81.10x = 8,606.60
  5. Step 5: Solve for x
    x = 8,606.60/81.10
  6. Step 6: Final answer
    x = 106.12

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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.