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Finding the Fourth Proportional to 139.20, 192.09 and 80.98

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Solution

The fourth proportional to 139.20, 192.09 and 80.98 is: 111.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.20 : 192.09 = 80.98 : x
  2. Step 2: Convert to fraction form
    139.20/192.09 = 80.98/x
  3. Step 3: Cross multiply
    139.20x = 192.09 × 80.98
  4. Step 4: Simplify right side
    139.20x = 15,555.45
  5. Step 5: Solve for x
    x = 15,555.45/139.20
  6. Step 6: Final answer
    x = 111.75

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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.