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Finding the Fourth Proportional to 81.54, 121.68 and 72.45

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Solution

The fourth proportional to 81.54, 121.68 and 72.45 is: 108.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.54 : 121.68 = 72.45 : x
  2. Step 2: Convert to fraction form
    81.54/121.68 = 72.45/x
  3. Step 3: Cross multiply
    81.54x = 121.68 × 72.45
  4. Step 4: Simplify right side
    81.54x = 8,815.72
  5. Step 5: Solve for x
    x = 8,815.72/81.54
  6. Step 6: Final answer
    x = 108.12

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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.