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Finding the Fourth Proportional to 139.70, 209.55 and 85.94

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Solution

The fourth proportional to 139.70, 209.55 and 85.94 is: 128.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.70 : 209.55 = 85.94 : x
  2. Step 2: Convert to fraction form
    139.70/209.55 = 85.94/x
  3. Step 3: Cross multiply
    139.70x = 209.55 × 85.94
  4. Step 4: Simplify right side
    139.70x = 18,008.73
  5. Step 5: Solve for x
    x = 18,008.73/139.70
  6. Step 6: Final answer
    x = 128.91

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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.