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Finding the Fourth Proportional to 813.78, 1,221.71 and 698.96

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Solution

The fourth proportional to 813.78, 1,221.71 and 698.96 is: 1,049.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.78 : 1,221.71 = 698.96 : x
  2. Step 2: Convert to fraction form
    813.78/1,221.71 = 698.96/x
  3. Step 3: Cross multiply
    813.78x = 1,221.71 × 698.96
  4. Step 4: Simplify right side
    813.78x = 853,916.82
  5. Step 5: Solve for x
    x = 853,916.82/813.78
  6. Step 6: Final answer
    x = 1,049.32

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.