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Finding the Fourth Proportional to 139.85, 208.68 and 138.63

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Solution

The fourth proportional to 139.85, 208.68 and 138.63 is: 206.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.85 : 208.68 = 138.63 : x
  2. Step 2: Convert to fraction form
    139.85/208.68 = 138.63/x
  3. Step 3: Cross multiply
    139.85x = 208.68 × 138.63
  4. Step 4: Simplify right side
    139.85x = 28,929.31
  5. Step 5: Solve for x
    x = 28,929.31/139.85
  6. Step 6: Final answer
    x = 206.86

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.