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Finding the Fourth Proportional to 138.94, 208.12 and 77.98

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Solution

The fourth proportional to 138.94, 208.12 and 77.98 is: 116.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.94 : 208.12 = 77.98 : x
  2. Step 2: Convert to fraction form
    138.94/208.12 = 77.98/x
  3. Step 3: Cross multiply
    138.94x = 208.12 × 77.98
  4. Step 4: Simplify right side
    138.94x = 16,229.20
  5. Step 5: Solve for x
    x = 16,229.20/138.94
  6. Step 6: Final answer
    x = 116.81

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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.