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Finding the Fourth Proportional to 721.88, 996.20 and 390.31

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Solution

The fourth proportional to 721.88, 996.20 and 390.31 is: 538.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.88 : 996.20 = 390.31 : x
  2. Step 2: Convert to fraction form
    721.88/996.20 = 390.31/x
  3. Step 3: Cross multiply
    721.88x = 996.20 × 390.31
  4. Step 4: Simplify right side
    721.88x = 388,822.00
  5. Step 5: Solve for x
    x = 388,822.00/721.88
  6. Step 6: Final answer
    x = 538.62

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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.