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Finding the Fourth Proportional to 627.78, 939.21 and 421.35

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Solution

The fourth proportional to 627.78, 939.21 and 421.35 is: 630.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    627.78 : 939.21 = 421.35 : x
  2. Step 2: Convert to fraction form
    627.78/939.21 = 421.35/x
  3. Step 3: Cross multiply
    627.78x = 939.21 × 421.35
  4. Step 4: Simplify right side
    627.78x = 395,736.13
  5. Step 5: Solve for x
    x = 395,736.13/627.78
  6. Step 6: Final answer
    x = 630.37

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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.