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Finding the Fourth Proportional to 206.80, 309.79 and 129.72

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Solution

The fourth proportional to 206.80, 309.79 and 129.72 is: 194.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.80 : 309.79 = 129.72 : x
  2. Step 2: Convert to fraction form
    206.80/309.79 = 129.72/x
  3. Step 3: Cross multiply
    206.80x = 309.79 × 129.72
  4. Step 4: Simplify right side
    206.80x = 40,185.96
  5. Step 5: Solve for x
    x = 40,185.96/206.80
  6. Step 6: Final answer
    x = 194.32

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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.