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Finding the Fourth Proportional to 138.92, 191.72 and 80.70

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Solution

The fourth proportional to 138.92, 191.72 and 80.70 is: 111.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.92 : 191.72 = 80.70 : x
  2. Step 2: Convert to fraction form
    138.92/191.72 = 80.70/x
  3. Step 3: Cross multiply
    138.92x = 191.72 × 80.70
  4. Step 4: Simplify right side
    138.92x = 15,472.72
  5. Step 5: Solve for x
    x = 15,472.72/138.92
  6. Step 6: Final answer
    x = 111.38

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.