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Finding the Fourth Proportional to 311.94, 428.19 and 287.30

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Solution

The fourth proportional to 311.94, 428.19 and 287.30 is: 394.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.94 : 428.19 = 287.30 : x
  2. Step 2: Convert to fraction form
    311.94/428.19 = 287.30/x
  3. Step 3: Cross multiply
    311.94x = 428.19 × 287.30
  4. Step 4: Simplify right side
    311.94x = 123,016.85
  5. Step 5: Solve for x
    x = 123,016.85/311.94
  6. Step 6: Final answer
    x = 394.36

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.