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Finding the Fourth Proportional to 390.87, 539.40 and 213.83

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Solution

The fourth proportional to 390.87, 539.40 and 213.83 is: 295.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.87 : 539.40 = 213.83 : x
  2. Step 2: Convert to fraction form
    390.87/539.40 = 213.83/x
  3. Step 3: Cross multiply
    390.87x = 539.40 × 213.83
  4. Step 4: Simplify right side
    390.87x = 115,339.90
  5. Step 5: Solve for x
    x = 115,339.90/390.87
  6. Step 6: Final answer
    x = 295.09

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.