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Finding the Fourth Proportional to 428.46, 642.06 and 211.61

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Solution

The fourth proportional to 428.46, 642.06 and 211.61 is: 317.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.46 : 642.06 = 211.61 : x
  2. Step 2: Convert to fraction form
    428.46/642.06 = 211.61/x
  3. Step 3: Cross multiply
    428.46x = 642.06 × 211.61
  4. Step 4: Simplify right side
    428.46x = 135,863.11
  5. Step 5: Solve for x
    x = 135,863.11/428.46
  6. Step 6: Final answer
    x = 317.10

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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.