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Finding the Fourth Proportional to 643.20, 887.72 and 381.28

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Solution

The fourth proportional to 643.20, 887.72 and 381.28 is: 526.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.20 : 887.72 = 381.28 : x
  2. Step 2: Convert to fraction form
    643.20/887.72 = 381.28/x
  3. Step 3: Cross multiply
    643.20x = 887.72 × 381.28
  4. Step 4: Simplify right side
    643.20x = 338,469.88
  5. Step 5: Solve for x
    x = 338,469.88/643.20
  6. Step 6: Final answer
    x = 526.23

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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.