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Finding the Fourth Proportional to 311.12, 428.94 and 287.66

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Solution

The fourth proportional to 311.12, 428.94 and 287.66 is: 396.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.12 : 428.94 = 287.66 : x
  2. Step 2: Convert to fraction form
    311.12/428.94 = 287.66/x
  3. Step 3: Cross multiply
    311.12x = 428.94 × 287.66
  4. Step 4: Simplify right side
    311.12x = 123,388.88
  5. Step 5: Solve for x
    x = 123,388.88/311.12
  6. Step 6: Final answer
    x = 396.60

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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.