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Finding the Fourth Proportional to 426.21, 639.34 and 206.80

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Solution

The fourth proportional to 426.21, 639.34 and 206.80 is: 310.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.21 : 639.34 = 206.80 : x
  2. Step 2: Convert to fraction form
    426.21/639.34 = 206.80/x
  3. Step 3: Cross multiply
    426.21x = 639.34 × 206.80
  4. Step 4: Simplify right side
    426.21x = 132,218.16
  5. Step 5: Solve for x
    x = 132,218.16/426.21
  6. Step 6: Final answer
    x = 310.22

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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.