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Finding the Fourth Proportional to 428.17, 642.06 and 211.66

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Solution

The fourth proportional to 428.17, 642.06 and 211.66 is: 317.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.17 : 642.06 = 211.66 : x
  2. Step 2: Convert to fraction form
    428.17/642.06 = 211.66/x
  3. Step 3: Cross multiply
    428.17x = 642.06 × 211.66
  4. Step 4: Simplify right side
    428.17x = 135,898.42
  5. Step 5: Solve for x
    x = 135,898.42/428.17
  6. Step 6: Final answer
    x = 317.39

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.