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Finding the Fourth Proportional to 138.85, 208.00 and 77.79

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Solution

The fourth proportional to 138.85, 208.00 and 77.79 is: 116.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.85 : 208.00 = 77.79 : x
  2. Step 2: Convert to fraction form
    138.85/208.00 = 77.79/x
  3. Step 3: Cross multiply
    138.85x = 208.00 × 77.79
  4. Step 4: Simplify right side
    138.85x = 16,181.20
  5. Step 5: Solve for x
    x = 16,181.20/138.85
  6. Step 6: Final answer
    x = 116.54

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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.