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Finding the Fourth Proportional to 206.75, 285.20 and 128.99

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Solution

The fourth proportional to 206.75, 285.20 and 128.99 is: 177.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.75 : 285.20 = 128.99 : x
  2. Step 2: Convert to fraction form
    206.75/285.20 = 128.99/x
  3. Step 3: Cross multiply
    206.75x = 285.20 × 128.99
  4. Step 4: Simplify right side
    206.75x = 36,786.52
  5. Step 5: Solve for x
    x = 36,786.52/206.75
  6. Step 6: Final answer
    x = 177.93

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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.