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Finding the Fourth Proportional to 81.08, 121.05 and 72.42

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Solution

The fourth proportional to 81.08, 121.05 and 72.42 is: 108.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.08 : 121.05 = 72.42 : x
  2. Step 2: Convert to fraction form
    81.08/121.05 = 72.42/x
  3. Step 3: Cross multiply
    81.08x = 121.05 × 72.42
  4. Step 4: Simplify right side
    81.08x = 8,766.44
  5. Step 5: Solve for x
    x = 8,766.44/81.08
  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.