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Finding the Fourth Proportional to 398.86, 550.59 and 390.76

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Solution

The fourth proportional to 398.86, 550.59 and 390.76 is: 539.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    398.86 : 550.59 = 390.76 : x
  2. Step 2: Convert to fraction form
    398.86/550.59 = 390.76/x
  3. Step 3: Cross multiply
    398.86x = 550.59 × 390.76
  4. Step 4: Simplify right side
    398.86x = 215,148.55
  5. Step 5: Solve for x
    x = 215,148.55/398.86
  6. Step 6: Final answer
    x = 539.41

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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.