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Finding the Fourth Proportional to 399.20, 550.80 and 231.15

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Solution

The fourth proportional to 399.20, 550.80 and 231.15 is: 318.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.20 : 550.80 = 231.15 : x
  2. Step 2: Convert to fraction form
    399.20/550.80 = 231.15/x
  3. Step 3: Cross multiply
    399.20x = 550.80 × 231.15
  4. Step 4: Simplify right side
    399.20x = 127,317.42
  5. Step 5: Solve for x
    x = 127,317.42/399.20
  6. Step 6: Final answer
    x = 318.93

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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.