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Finding the Fourth Proportional to 390.89, 539.42 and 213.85

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Solution

The fourth proportional to 390.89, 539.42 and 213.85 is: 295.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.89 : 539.42 = 213.85 : x
  2. Step 2: Convert to fraction form
    390.89/539.42 = 213.85/x
  3. Step 3: Cross multiply
    390.89x = 539.42 × 213.85
  4. Step 4: Simplify right side
    390.89x = 115,351.20
  5. Step 5: Solve for x
    x = 115,351.20/390.89
  6. Step 6: Final answer
    x = 295.10

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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.