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Finding the Fourth Proportional to 641.28, 885.36 and 408.72

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Solution

The fourth proportional to 641.28, 885.36 and 408.72 is: 564.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.28 : 885.36 = 408.72 : x
  2. Step 2: Convert to fraction form
    641.28/885.36 = 408.72/x
  3. Step 3: Cross multiply
    641.28x = 885.36 × 408.72
  4. Step 4: Simplify right side
    641.28x = 361,864.34
  5. Step 5: Solve for x
    x = 361,864.34/641.28
  6. Step 6: Final answer
    x = 564.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.