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Finding the Fourth Proportional to 138.77, 208.19 and 80.87

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Solution

The fourth proportional to 138.77, 208.19 and 80.87 is: 121.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.77 : 208.19 = 80.87 : x
  2. Step 2: Convert to fraction form
    138.77/208.19 = 80.87/x
  3. Step 3: Cross multiply
    138.77x = 208.19 × 80.87
  4. Step 4: Simplify right side
    138.77x = 16,835.49
  5. Step 5: Solve for x
    x = 16,835.49/138.77
  6. Step 6: Final answer
    x = 121.32

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.