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Finding the Fourth Proportional to 396.20, 546.78 and 221.57

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Solution

The fourth proportional to 396.20, 546.78 and 221.57 is: 305.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    396.20 : 546.78 = 221.57 : x
  2. Step 2: Convert to fraction form
    396.20/546.78 = 221.57/x
  3. Step 3: Cross multiply
    396.20x = 546.78 × 221.57
  4. Step 4: Simplify right side
    396.20x = 121,147.31
  5. Step 5: Solve for x
    x = 121,147.31/396.20
  6. Step 6: Final answer
    x = 305.78

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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.