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Finding the Fourth Proportional to 428.82, 643.17 and 319.28

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Solution

The fourth proportional to 428.82, 643.17 and 319.28 is: 478.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.82 : 643.17 = 319.28 : x
  2. Step 2: Convert to fraction form
    428.82/643.17 = 319.28/x
  3. Step 3: Cross multiply
    428.82x = 643.17 × 319.28
  4. Step 4: Simplify right side
    428.82x = 205,348.10
  5. Step 5: Solve for x
    x = 205,348.10/428.82
  6. Step 6: Final answer
    x = 478.87

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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.