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Finding the Fourth Proportional to 206.50, 285 and 128.86

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Solution

The fourth proportional to 206.50, 285 and 128.86 is: 177.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.50 : 285 = 128.86 : x
  2. Step 2: Convert to fraction form
    206.50/285 = 128.86/x
  3. Step 3: Cross multiply
    206.50x = 285 × 128.86
  4. Step 4: Simplify right side
    206.50x = 36,725.10
  5. Step 5: Solve for x
    x = 36,725.10/206.50
  6. Step 6: Final answer
    x = 177.85

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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.