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Finding the Fourth Proportional to 81.66, 121.60 and 76.47

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Solution

The fourth proportional to 81.66, 121.60 and 76.47 is: 113.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.66 : 121.60 = 76.47 : x
  2. Step 2: Convert to fraction form
    81.66/121.60 = 76.47/x
  3. Step 3: Cross multiply
    81.66x = 121.60 × 76.47
  4. Step 4: Simplify right side
    81.66x = 9,298.75
  5. Step 5: Solve for x
    x = 9,298.75/81.66
  6. Step 6: Final answer
    x = 113.87

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.