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Finding the Fourth Proportional to 139.39, 209.02 and 81.66

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Solution

The fourth proportional to 139.39, 209.02 and 81.66 is: 122.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.39 : 209.02 = 81.66 : x
  2. Step 2: Convert to fraction form
    139.39/209.02 = 81.66/x
  3. Step 3: Cross multiply
    139.39x = 209.02 × 81.66
  4. Step 4: Simplify right side
    139.39x = 17,068.57
  5. Step 5: Solve for x
    x = 17,068.57/139.39
  6. Step 6: Final answer
    x = 122.45

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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.