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Finding the Fourth Proportional to 426.87, 639.50 and 209.79

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Solution

The fourth proportional to 426.87, 639.50 and 209.79 is: 314.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.87 : 639.50 = 209.79 : x
  2. Step 2: Convert to fraction form
    426.87/639.50 = 209.79/x
  3. Step 3: Cross multiply
    426.87x = 639.50 × 209.79
  4. Step 4: Simplify right side
    426.87x = 134,159.66
  5. Step 5: Solve for x
    x = 134,159.66/426.87
  6. Step 6: Final answer
    x = 314.29

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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.