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Finding the Fourth Proportional to 338.78, 508.20 and 261.80

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Solution

The fourth proportional to 338.78, 508.20 and 261.80 is: 392.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    338.78 : 508.20 = 261.80 : x
  2. Step 2: Convert to fraction form
    338.78/508.20 = 261.80/x
  3. Step 3: Cross multiply
    338.78x = 508.20 × 261.80
  4. Step 4: Simplify right side
    338.78x = 133,046.76
  5. Step 5: Solve for x
    x = 133,046.76/338.78
  6. Step 6: Final answer
    x = 392.72

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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.