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Finding the Fourth Proportional to 639.68, 959.34 and 206.78

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Solution

The fourth proportional to 639.68, 959.34 and 206.78 is: 310.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.68 : 959.34 = 206.78 : x
  2. Step 2: Convert to fraction form
    639.68/959.34 = 206.78/x
  3. Step 3: Cross multiply
    639.68x = 959.34 × 206.78
  4. Step 4: Simplify right side
    639.68x = 198,372.33
  5. Step 5: Solve for x
    x = 198,372.33/639.68
  6. Step 6: Final answer
    x = 310.11

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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.