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Finding the Fourth Proportional to 398.78, 550.30 and 221.76

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Solution

The fourth proportional to 398.78, 550.30 and 221.76 is: 306.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.78 : 550.30 = 221.76 : x
  2. Step 2: Convert to fraction form
    398.78/550.30 = 221.76/x
  3. Step 3: Cross multiply
    398.78x = 550.30 × 221.76
  4. Step 4: Simplify right side
    398.78x = 122,034.53
  5. Step 5: Solve for x
    x = 122,034.53/398.78
  6. Step 6: Final answer
    x = 306.02

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.