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Finding the Fourth Proportional to 390.90, 539.44 and 213.86

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Solution

The fourth proportional to 390.90, 539.44 and 213.86 is: 295.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.90 : 539.44 = 213.86 : x
  2. Step 2: Convert to fraction form
    390.90/539.44 = 213.86/x
  3. Step 3: Cross multiply
    390.90x = 539.44 × 213.86
  4. Step 4: Simplify right side
    390.90x = 115,360.87
  5. Step 5: Solve for x
    x = 115,360.87/390.90
  6. Step 6: Final answer
    x = 295.12

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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.