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Finding the Fourth Proportional to 402.78, 604.19 and 128.80

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Solution

The fourth proportional to 402.78, 604.19 and 128.80 is: 193.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    402.78 : 604.19 = 128.80 : x
  2. Step 2: Convert to fraction form
    402.78/604.19 = 128.80/x
  3. Step 3: Cross multiply
    402.78x = 604.19 × 128.80
  4. Step 4: Simplify right side
    402.78x = 77,819.67
  5. Step 5: Solve for x
    x = 77,819.67/402.78
  6. Step 6: Final answer
    x = 193.21

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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.