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Finding the Fourth Proportional to 139.20, 209.88 and 121.98

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Solution

The fourth proportional to 139.20, 209.88 and 121.98 is: 183.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.20 : 209.88 = 121.98 : x
  2. Step 2: Convert to fraction form
    139.20/209.88 = 121.98/x
  3. Step 3: Cross multiply
    139.20x = 209.88 × 121.98
  4. Step 4: Simplify right side
    139.20x = 25,601.16
  5. Step 5: Solve for x
    x = 25,601.16/139.20
  6. Step 6: Final answer
    x = 183.92

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.