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Finding the Fourth Proportional to 89.81, 134.42 and 81.39

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Solution

The fourth proportional to 89.81, 134.42 and 81.39 is: 121.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.81 : 134.42 = 81.39 : x
  2. Step 2: Convert to fraction form
    89.81/134.42 = 81.39/x
  3. Step 3: Cross multiply
    89.81x = 134.42 × 81.39
  4. Step 4: Simplify right side
    89.81x = 10,940.44
  5. Step 5: Solve for x
    x = 10,940.44/89.81
  6. Step 6: Final answer
    x = 121.82

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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.