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Finding the Fourth Proportional to 728.36, 1,005.12 and 396.80

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Solution

The fourth proportional to 728.36, 1,005.12 and 396.80 is: 547.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.36 : 1,005.12 = 396.80 : x
  2. Step 2: Convert to fraction form
    728.36/1,005.12 = 396.80/x
  3. Step 3: Cross multiply
    728.36x = 1,005.12 × 396.80
  4. Step 4: Simplify right side
    728.36x = 398,834.13
  5. Step 5: Solve for x
    x = 398,834.13/728.36
  6. Step 6: Final answer
    x = 547.58

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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.