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Finding the Fourth Proportional to 138.69, 208.08 and 77.87

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Solution

The fourth proportional to 138.69, 208.08 and 77.87 is: 116.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.69 : 208.08 = 77.87 : x
  2. Step 2: Convert to fraction form
    138.69/208.08 = 77.87/x
  3. Step 3: Cross multiply
    138.69x = 208.08 × 77.87
  4. Step 4: Simplify right side
    138.69x = 16,202.15
  5. Step 5: Solve for x
    x = 16,202.15/138.69
  6. Step 6: Final answer
    x = 116.82

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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.