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Finding the Fourth Proportional to 428.17, 641.74 and 208.75

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Solution

The fourth proportional to 428.17, 641.74 and 208.75 is: 312.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.17 : 641.74 = 208.75 : x
  2. Step 2: Convert to fraction form
    428.17/641.74 = 208.75/x
  3. Step 3: Cross multiply
    428.17x = 641.74 × 208.75
  4. Step 4: Simplify right side
    428.17x = 133,963.23
  5. Step 5: Solve for x
    x = 133,963.23/428.17
  6. Step 6: Final answer
    x = 312.87

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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.