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Finding the Fourth Proportional to 81.44, 121.52 and 72.78

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Solution

The fourth proportional to 81.44, 121.52 and 72.78 is: 108.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.44 : 121.52 = 72.78 : x
  2. Step 2: Convert to fraction form
    81.44/121.52 = 72.78/x
  3. Step 3: Cross multiply
    81.44x = 121.52 × 72.78
  4. Step 4: Simplify right side
    81.44x = 8,844.47
  5. Step 5: Solve for x
    x = 8,844.47/81.44
  6. Step 6: Final answer
    x = 108.61

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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.