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Finding the Fourth Proportional to 206.78, 285.42 and 129.22

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Solution

The fourth proportional to 206.78, 285.42 and 129.22 is: 178.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.78 : 285.42 = 129.22 : x
  2. Step 2: Convert to fraction form
    206.78/285.42 = 129.22/x
  3. Step 3: Cross multiply
    206.78x = 285.42 × 129.22
  4. Step 4: Simplify right side
    206.78x = 36,881.97
  5. Step 5: Solve for x
    x = 36,881.97/206.78
  6. Step 6: Final answer
    x = 178.36

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.