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Finding the Fourth Proportional to 81.16, 111.78 and 80.68

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Solution

The fourth proportional to 81.16, 111.78 and 80.68 is: 111.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 111.78 = 80.68 : x
  2. Step 2: Convert to fraction form
    81.16/111.78 = 80.68/x
  3. Step 3: Cross multiply
    81.16x = 111.78 × 80.68
  4. Step 4: Simplify right side
    81.16x = 9,018.41
  5. Step 5: Solve for x
    x = 9,018.41/81.16
  6. Step 6: Final answer
    x = 111.12

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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.