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Finding the Fourth Proportional to 81.62, 121.61 and 77.54

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Solution

The fourth proportional to 81.62, 121.61 and 77.54 is: 115.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.62 : 121.61 = 77.54 : x
  2. Step 2: Convert to fraction form
    81.62/121.61 = 77.54/x
  3. Step 3: Cross multiply
    81.62x = 121.61 × 77.54
  4. Step 4: Simplify right side
    81.62x = 9,429.25
  5. Step 5: Solve for x
    x = 9,429.25/81.62
  6. Step 6: Final answer
    x = 115.53

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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.