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Finding the Fourth Proportional to 419.21, 628.85 and 213.78

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Solution

The fourth proportional to 419.21, 628.85 and 213.78 is: 320.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    419.21 : 628.85 = 213.78 : x
  2. Step 2: Convert to fraction form
    419.21/628.85 = 213.78/x
  3. Step 3: Cross multiply
    419.21x = 628.85 × 213.78
  4. Step 4: Simplify right side
    419.21x = 134,436.09
  5. Step 5: Solve for x
    x = 134,436.09/419.21
  6. Step 6: Final answer
    x = 320.69

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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.