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Finding the Fourth Proportional to 728.45, 1,005.28 and 396.89

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Solution

The fourth proportional to 728.45, 1,005.28 and 396.89 is: 547.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.45 : 1,005.28 = 396.89 : x
  2. Step 2: Convert to fraction form
    728.45/1,005.28 = 396.89/x
  3. Step 3: Cross multiply
    728.45x = 1,005.28 × 396.89
  4. Step 4: Simplify right side
    728.45x = 398,979.56
  5. Step 5: Solve for x
    x = 398,979.56/728.45
  6. Step 6: Final answer
    x = 547.71

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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.