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Finding the Fourth Proportional to 426.13, 639.20 and 206.78

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Solution

The fourth proportional to 426.13, 639.20 and 206.78 is: 310.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.13 : 639.20 = 206.78 : x
  2. Step 2: Convert to fraction form
    426.13/639.20 = 206.78/x
  3. Step 3: Cross multiply
    426.13x = 639.20 × 206.78
  4. Step 4: Simplify right side
    426.13x = 132,173.78
  5. Step 5: Solve for x
    x = 132,173.78/426.13
  6. Step 6: Final answer
    x = 310.17

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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.