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Finding the Fourth Proportional to 721.38, 1,002.41 and 712.20

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Solution

The fourth proportional to 721.38, 1,002.41 and 712.20 is: 989.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.38 : 1,002.41 = 712.20 : x
  2. Step 2: Convert to fraction form
    721.38/1,002.41 = 712.20/x
  3. Step 3: Cross multiply
    721.38x = 1,002.41 × 712.20
  4. Step 4: Simplify right side
    721.38x = 713,912.84
  5. Step 5: Solve for x
    x = 713,912.84/721.38
  6. Step 6: Final answer
    x = 989.65

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.