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Finding the Fourth Proportional to 220.80, 331.20 and 139.39

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Solution

The fourth proportional to 220.80, 331.20 and 139.39 is: 209.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    220.80 : 331.20 = 139.39 : x
  2. Step 2: Convert to fraction form
    220.80/331.20 = 139.39/x
  3. Step 3: Cross multiply
    220.80x = 331.20 × 139.39
  4. Step 4: Simplify right side
    220.80x = 46,165.97
  5. Step 5: Solve for x
    x = 46,165.97/220.80
  6. Step 6: Final answer
    x = 209.09

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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.