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Finding the Fourth Proportional to 428.67, 642.09 and 208.96

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Solution

The fourth proportional to 428.67, 642.09 and 208.96 is: 312.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.67 : 642.09 = 208.96 : x
  2. Step 2: Convert to fraction form
    428.67/642.09 = 208.96/x
  3. Step 3: Cross multiply
    428.67x = 642.09 × 208.96
  4. Step 4: Simplify right side
    428.67x = 134,169.52
  5. Step 5: Solve for x
    x = 134,169.52/428.67
  6. Step 6: Final answer
    x = 312.99

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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.