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Finding the Fourth Proportional to 339.78, 509.40 and 285.78

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Solution

The fourth proportional to 339.78, 509.40 and 285.78 is: 428.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    339.78 : 509.40 = 285.78 : x
  2. Step 2: Convert to fraction form
    339.78/509.40 = 285.78/x
  3. Step 3: Cross multiply
    339.78x = 509.40 × 285.78
  4. Step 4: Simplify right side
    339.78x = 145,576.33
  5. Step 5: Solve for x
    x = 145,576.33/339.78
  6. Step 6: Final answer
    x = 428.44

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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.