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Finding the Fourth Proportional to 399.35, 550.45 and 311.87

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Solution

The fourth proportional to 399.35, 550.45 and 311.87 is: 429.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.35 : 550.45 = 311.87 : x
  2. Step 2: Convert to fraction form
    399.35/550.45 = 311.87/x
  3. Step 3: Cross multiply
    399.35x = 550.45 × 311.87
  4. Step 4: Simplify right side
    399.35x = 171,668.84
  5. Step 5: Solve for x
    x = 171,668.84/399.35
  6. Step 6: Final answer
    x = 429.87

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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.