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Finding the Fourth Proportional to 821.89, 1,229.09 and 613.80

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Solution

The fourth proportional to 821.89, 1,229.09 and 613.80 is: 917.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.89 : 1,229.09 = 613.80 : x
  2. Step 2: Convert to fraction form
    821.89/1,229.09 = 613.80/x
  3. Step 3: Cross multiply
    821.89x = 1,229.09 × 613.80
  4. Step 4: Simplify right side
    821.89x = 754,412.37
  5. Step 5: Solve for x
    x = 754,412.37/821.89
  6. Step 6: Final answer
    x = 917.90

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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.