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Finding the Fourth Proportional to 428.28, 639.75 and 311.73

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Solution

The fourth proportional to 428.28, 639.75 and 311.73 is: 465.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.28 : 639.75 = 311.73 : x
  2. Step 2: Convert to fraction form
    428.28/639.75 = 311.73/x
  3. Step 3: Cross multiply
    428.28x = 639.75 × 311.73
  4. Step 4: Simplify right side
    428.28x = 199,429.27
  5. Step 5: Solve for x
    x = 199,429.27/428.28
  6. Step 6: Final answer
    x = 465.65

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.