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Finding the Fourth Proportional to 814.91, 1,121.71 and 721.49

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Solution

The fourth proportional to 814.91, 1,121.71 and 721.49 is: 993.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    814.91 : 1,121.71 = 721.49 : x
  2. Step 2: Convert to fraction form
    814.91/1,121.71 = 721.49/x
  3. Step 3: Cross multiply
    814.91x = 1,121.71 × 721.49
  4. Step 4: Simplify right side
    814.91x = 809,296.94
  5. Step 5: Solve for x
    x = 809,296.94/814.91
  6. Step 6: Final answer
    x = 993.12

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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.