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Finding the Fourth Proportional to 481.21, 721.78 and 139.21

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Solution

The fourth proportional to 481.21, 721.78 and 139.21 is: 208.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    481.21 : 721.78 = 139.21 : x
  2. Step 2: Convert to fraction form
    481.21/721.78 = 139.21/x
  3. Step 3: Cross multiply
    481.21x = 721.78 × 139.21
  4. Step 4: Simplify right side
    481.21x = 100,478.99
  5. Step 5: Solve for x
    x = 100,478.99/481.21
  6. Step 6: Final answer
    x = 208.80

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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.