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Finding the Fourth Proportional to 81.29, 111.69 and 66.71

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Solution

The fourth proportional to 81.29, 111.69 and 66.71 is: 91.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.29 : 111.69 = 66.71 : x
  2. Step 2: Convert to fraction form
    81.29/111.69 = 66.71/x
  3. Step 3: Cross multiply
    81.29x = 111.69 × 66.71
  4. Step 4: Simplify right side
    81.29x = 7,451.12
  5. Step 5: Solve for x
    x = 7,451.12/81.29
  6. Step 6: Final answer
    x = 91.66

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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.