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Finding the Fourth Proportional to 721.89, 996.21 and 390.32

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Solution

The fourth proportional to 721.89, 996.21 and 390.32 is: 538.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.89 : 996.21 = 390.32 : x
  2. Step 2: Convert to fraction form
    721.89/996.21 = 390.32/x
  3. Step 3: Cross multiply
    721.89x = 996.21 × 390.32
  4. Step 4: Simplify right side
    721.89x = 388,842.77
  5. Step 5: Solve for x
    x = 388,842.77/721.89
  6. Step 6: Final answer
    x = 538.65

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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.