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Finding the Fourth Proportional to 813.69, 1,221.75 and 789.39

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Solution

The fourth proportional to 813.69, 1,221.75 and 789.39 is: 1,185.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.69 : 1,221.75 = 789.39 : x
  2. Step 2: Convert to fraction form
    813.69/1,221.75 = 789.39/x
  3. Step 3: Cross multiply
    813.69x = 1,221.75 × 789.39
  4. Step 4: Simplify right side
    813.69x = 964,437.23
  5. Step 5: Solve for x
    x = 964,437.23/813.69
  6. Step 6: Final answer
    x = 1,185.26

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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.