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Finding the Fourth Proportional to 139.36, 208.87 and 78.55

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Solution

The fourth proportional to 139.36, 208.87 and 78.55 is: 117.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.36 : 208.87 = 78.55 : x
  2. Step 2: Convert to fraction form
    139.36/208.87 = 78.55/x
  3. Step 3: Cross multiply
    139.36x = 208.87 × 78.55
  4. Step 4: Simplify right side
    139.36x = 16,406.74
  5. Step 5: Solve for x
    x = 16,406.74/139.36
  6. Step 6: Final answer
    x = 117.73

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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.