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Finding the Fourth Proportional to 311.07, 428.78 and 212.66

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Solution

The fourth proportional to 311.07, 428.78 and 212.66 is: 293.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.07 : 428.78 = 212.66 : x
  2. Step 2: Convert to fraction form
    311.07/428.78 = 212.66/x
  3. Step 3: Cross multiply
    311.07x = 428.78 × 212.66
  4. Step 4: Simplify right side
    311.07x = 91,181.15
  5. Step 5: Solve for x
    x = 91,181.15/311.07
  6. Step 6: Final answer
    x = 293.12

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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.