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Finding the Fourth Proportional to 418.78, 628.20 and 213.20

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Solution

The fourth proportional to 418.78, 628.20 and 213.20 is: 319.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    418.78 : 628.20 = 213.20 : x
  2. Step 2: Convert to fraction form
    418.78/628.20 = 213.20/x
  3. Step 3: Cross multiply
    418.78x = 628.20 × 213.20
  4. Step 4: Simplify right side
    418.78x = 133,932.24
  5. Step 5: Solve for x
    x = 133,932.24/418.78
  6. Step 6: Final answer
    x = 319.82

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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.