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Finding the Fourth Proportional to 206.10, 309.42 and 128.85

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Solution

The fourth proportional to 206.10, 309.42 and 128.85 is: 193.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.10 : 309.42 = 128.85 : x
  2. Step 2: Convert to fraction form
    206.10/309.42 = 128.85/x
  3. Step 3: Cross multiply
    206.10x = 309.42 × 128.85
  4. Step 4: Simplify right side
    206.10x = 39,868.77
  5. Step 5: Solve for x
    x = 39,868.77/206.10
  6. Step 6: Final answer
    x = 193.44

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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.