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Finding the Fourth Proportional to 81.29, 111.89 and 81.15

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Solution

The fourth proportional to 81.29, 111.89 and 81.15 is: 111.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.29 : 111.89 = 81.15 : x
  2. Step 2: Convert to fraction form
    81.29/111.89 = 81.15/x
  3. Step 3: Cross multiply
    81.29x = 111.89 × 81.15
  4. Step 4: Simplify right side
    81.29x = 9,079.47
  5. Step 5: Solve for x
    x = 9,079.47/81.29
  6. Step 6: Final answer
    x = 111.70

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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.