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Finding the Fourth Proportional to 206.70, 309.42 and 129.40

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Solution

The fourth proportional to 206.70, 309.42 and 129.40 is: 193.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.70 : 309.42 = 129.40 : x
  2. Step 2: Convert to fraction form
    206.70/309.42 = 129.40/x
  3. Step 3: Cross multiply
    206.70x = 309.42 × 129.40
  4. Step 4: Simplify right side
    206.70x = 40,038.17
  5. Step 5: Solve for x
    x = 40,038.17/206.70
  6. Step 6: Final answer
    x = 193.70

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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.