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Finding the Fourth Proportional to 81.17, 121.47 and 66.55

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Solution

The fourth proportional to 81.17, 121.47 and 66.55 is: 99.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.17 : 121.47 = 66.55 : x
  2. Step 2: Convert to fraction form
    81.17/121.47 = 66.55/x
  3. Step 3: Cross multiply
    81.17x = 121.47 × 66.55
  4. Step 4: Simplify right side
    81.17x = 8,083.22
  5. Step 5: Solve for x
    x = 8,083.22/81.17
  6. Step 6: Final answer
    x = 99.58

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.