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Finding the Fourth Proportional to 81.07, 121.46 and 72.43

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Solution

The fourth proportional to 81.07, 121.46 and 72.43 is: 108.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.07 : 121.46 = 72.43 : x
  2. Step 2: Convert to fraction form
    81.07/121.46 = 72.43/x
  3. Step 3: Cross multiply
    81.07x = 121.46 × 72.43
  4. Step 4: Simplify right side
    81.07x = 8,796.38
  5. Step 5: Solve for x
    x = 8,796.38/81.07
  6. Step 6: Final answer
    x = 108.50

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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.