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Finding the Fourth Proportional to 639.38, 959.20 and 206.57

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Solution

The fourth proportional to 639.38, 959.20 and 206.57 is: 309.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.38 : 959.20 = 206.57 : x
  2. Step 2: Convert to fraction form
    639.38/959.20 = 206.57/x
  3. Step 3: Cross multiply
    639.38x = 959.20 × 206.57
  4. Step 4: Simplify right side
    639.38x = 198,141.94
  5. Step 5: Solve for x
    x = 198,141.94/639.38
  6. Step 6: Final answer
    x = 309.90

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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.