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Finding the Fourth Proportional to 81.76, 121.94 and 71.38

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Solution

The fourth proportional to 81.76, 121.94 and 71.38 is: 106.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.76 : 121.94 = 71.38 : x
  2. Step 2: Convert to fraction form
    81.76/121.94 = 71.38/x
  3. Step 3: Cross multiply
    81.76x = 121.94 × 71.38
  4. Step 4: Simplify right side
    81.76x = 8,704.08
  5. Step 5: Solve for x
    x = 8,704.08/81.76
  6. Step 6: Final answer
    x = 106.46

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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.