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Finding the Fourth Proportional to 138.20, 190.86 and 105.56

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Solution

The fourth proportional to 138.20, 190.86 and 105.56 is: 145.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.20 : 190.86 = 105.56 : x
  2. Step 2: Convert to fraction form
    138.20/190.86 = 105.56/x
  3. Step 3: Cross multiply
    138.20x = 190.86 × 105.56
  4. Step 4: Simplify right side
    138.20x = 20,147.18
  5. Step 5: Solve for x
    x = 20,147.18/138.20
  6. Step 6: Final answer
    x = 145.78

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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.