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Finding the Fourth Proportional to 728.90, 1,005.90 and 397.35

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Solution

The fourth proportional to 728.90, 1,005.90 and 397.35 is: 548.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.90 : 1,005.90 = 397.35 : x
  2. Step 2: Convert to fraction form
    728.90/1,005.90 = 397.35/x
  3. Step 3: Cross multiply
    728.90x = 1,005.90 × 397.35
  4. Step 4: Simplify right side
    728.90x = 399,694.37
  5. Step 5: Solve for x
    x = 399,694.37/728.90
  6. Step 6: Final answer
    x = 548.36

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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.