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Finding the Fourth Proportional to 139.14, 208.74 and 78.27

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Solution

The fourth proportional to 139.14, 208.74 and 78.27 is: 117.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.14 : 208.74 = 78.27 : x
  2. Step 2: Convert to fraction form
    139.14/208.74 = 78.27/x
  3. Step 3: Cross multiply
    139.14x = 208.74 × 78.27
  4. Step 4: Simplify right side
    139.14x = 16,338.08
  5. Step 5: Solve for x
    x = 16,338.08/139.14
  6. Step 6: Final answer
    x = 117.42

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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.