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Finding the Fourth Proportional to 639.30, 958.86 and 206.40

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Solution

The fourth proportional to 639.30, 958.86 and 206.40 is: 309.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.30 : 958.86 = 206.40 : x
  2. Step 2: Convert to fraction form
    639.30/958.86 = 206.40/x
  3. Step 3: Cross multiply
    639.30x = 958.86 × 206.40
  4. Step 4: Simplify right side
    639.30x = 197,908.70
  5. Step 5: Solve for x
    x = 197,908.70/639.30
  6. Step 6: Final answer
    x = 309.57

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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.