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Finding the Fourth Proportional to 399.70, 550.39 and 390.60

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Solution

The fourth proportional to 399.70, 550.39 and 390.60 is: 537.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.70 : 550.39 = 390.60 : x
  2. Step 2: Convert to fraction form
    399.70/550.39 = 390.60/x
  3. Step 3: Cross multiply
    399.70x = 550.39 × 390.60
  4. Step 4: Simplify right side
    399.70x = 214,981.36
  5. Step 5: Solve for x
    x = 214,981.36/399.70
  6. Step 6: Final answer
    x = 537.86

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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.