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Finding the Fourth Proportional to 428.47, 642.89 and 208.97

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Solution

The fourth proportional to 428.47, 642.89 and 208.97 is: 313.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.47 : 642.89 = 208.97 : x
  2. Step 2: Convert to fraction form
    428.47/642.89 = 208.97/x
  3. Step 3: Cross multiply
    428.47x = 642.89 × 208.97
  4. Step 4: Simplify right side
    428.47x = 134,344.72
  5. Step 5: Solve for x
    x = 134,344.72/428.47
  6. Step 6: Final answer
    x = 313.55

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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.