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Finding the Fourth Proportional to 139.39, 209.92 and 121.57

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Solution

The fourth proportional to 139.39, 209.92 and 121.57 is: 183.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.39 : 209.92 = 121.57 : x
  2. Step 2: Convert to fraction form
    139.39/209.92 = 121.57/x
  3. Step 3: Cross multiply
    139.39x = 209.92 × 121.57
  4. Step 4: Simplify right side
    139.39x = 25,519.97
  5. Step 5: Solve for x
    x = 25,519.97/139.39
  6. Step 6: Final answer
    x = 183.08

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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.