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Finding the Fourth Proportional to 831, 1,245.78 and 419.88

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Solution

The fourth proportional to 831, 1,245.78 and 419.88 is: 629.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    831 : 1,245.78 = 419.88 : x
  2. Step 2: Convert to fraction form
    831/1,245.78 = 419.88/x
  3. Step 3: Cross multiply
    831x = 1,245.78 × 419.88
  4. Step 4: Simplify right side
    831x = 523,078.11
  5. Step 5: Solve for x
    x = 523,078.11/831
  6. Step 6: Final answer
    x = 629.46

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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.