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Finding the Fourth Proportional to 206.72, 285.19 and 128.96

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Solution

The fourth proportional to 206.72, 285.19 and 128.96 is: 177.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.72 : 285.19 = 128.96 : x
  2. Step 2: Convert to fraction form
    206.72/285.19 = 128.96/x
  3. Step 3: Cross multiply
    206.72x = 285.19 × 128.96
  4. Step 4: Simplify right side
    206.72x = 36,776.35
  5. Step 5: Solve for x
    x = 36,776.35/206.72
  6. Step 6: Final answer
    x = 177.91

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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.