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Finding the Fourth Proportional to 206.45, 309.60 and 129.90

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Solution

The fourth proportional to 206.45, 309.60 and 129.90 is: 194.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.45 : 309.60 = 129.90 : x
  2. Step 2: Convert to fraction form
    206.45/309.60 = 129.90/x
  3. Step 3: Cross multiply
    206.45x = 309.60 × 129.90
  4. Step 4: Simplify right side
    206.45x = 40,217.04
  5. Step 5: Solve for x
    x = 40,217.04/206.45
  6. Step 6: Final answer
    x = 194.81

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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.