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Finding the Fourth Proportional to 139.12, 208.51 and 81.37

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Solution

The fourth proportional to 139.12, 208.51 and 81.37 is: 121.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.12 : 208.51 = 81.37 : x
  2. Step 2: Convert to fraction form
    139.12/208.51 = 81.37/x
  3. Step 3: Cross multiply
    139.12x = 208.51 × 81.37
  4. Step 4: Simplify right side
    139.12x = 16,966.46
  5. Step 5: Solve for x
    x = 16,966.46/139.12
  6. Step 6: Final answer
    x = 121.96

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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.