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Finding the Fourth Proportional to 822.78, 1,234.20 and 389.64

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Solution

The fourth proportional to 822.78, 1,234.20 and 389.64 is: 584.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    822.78 : 1,234.20 = 389.64 : x
  2. Step 2: Convert to fraction form
    822.78/1,234.20 = 389.64/x
  3. Step 3: Cross multiply
    822.78x = 1,234.20 × 389.64
  4. Step 4: Simplify right side
    822.78x = 480,893.69
  5. Step 5: Solve for x
    x = 480,893.69/822.78
  6. Step 6: Final answer
    x = 584.47

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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.