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Finding the Fourth Proportional to 139.45, 209.06 and 81.53

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Solution

The fourth proportional to 139.45, 209.06 and 81.53 is: 122.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.45 : 209.06 = 81.53 : x
  2. Step 2: Convert to fraction form
    139.45/209.06 = 81.53/x
  3. Step 3: Cross multiply
    139.45x = 209.06 × 81.53
  4. Step 4: Simplify right side
    139.45x = 17,044.25
  5. Step 5: Solve for x
    x = 17,044.25/139.45
  6. Step 6: Final answer
    x = 122.22

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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.