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Finding the Fourth Proportional to 138.69, 191.39 and 80.47

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Solution

The fourth proportional to 138.69, 191.39 and 80.47 is: 111.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.69 : 191.39 = 80.47 : x
  2. Step 2: Convert to fraction form
    138.69/191.39 = 80.47/x
  3. Step 3: Cross multiply
    138.69x = 191.39 × 80.47
  4. Step 4: Simplify right side
    138.69x = 15,401.15
  5. Step 5: Solve for x
    x = 15,401.15/138.69
  6. Step 6: Final answer
    x = 111.05

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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.