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Finding the Fourth Proportional to 639.40, 959.19 and 206.50

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Solution

The fourth proportional to 639.40, 959.19 and 206.50 is: 309.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.40 : 959.19 = 206.50 : x
  2. Step 2: Convert to fraction form
    639.40/959.19 = 206.50/x
  3. Step 3: Cross multiply
    639.40x = 959.19 × 206.50
  4. Step 4: Simplify right side
    639.40x = 198,072.74
  5. Step 5: Solve for x
    x = 198,072.74/639.40
  6. Step 6: Final answer
    x = 309.78

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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.