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Finding the Fourth Proportional to 311.05, 428.81 and 212.65

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Solution

The fourth proportional to 311.05, 428.81 and 212.65 is: 293.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.05 : 428.81 = 212.65 : x
  2. Step 2: Convert to fraction form
    311.05/428.81 = 212.65/x
  3. Step 3: Cross multiply
    311.05x = 428.81 × 212.65
  4. Step 4: Simplify right side
    311.05x = 91,185.38
  5. Step 5: Solve for x
    x = 91,185.38/311.05
  6. Step 6: Final answer
    x = 293.15

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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.