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Finding the Fourth Proportional to 81.58, 121.89 and 66.96

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Solution

The fourth proportional to 81.58, 121.89 and 66.96 is: 100.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.58 : 121.89 = 66.96 : x
  2. Step 2: Convert to fraction form
    81.58/121.89 = 66.96/x
  3. Step 3: Cross multiply
    81.58x = 121.89 × 66.96
  4. Step 4: Simplify right side
    81.58x = 8,161.75
  5. Step 5: Solve for x
    x = 8,161.75/81.58
  6. Step 6: Final answer
    x = 100.05

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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.