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Finding the Fourth Proportional to 821.38, 1,229.64 and 561.64

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Solution

The fourth proportional to 821.38, 1,229.64 and 561.64 is: 840.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.38 : 1,229.64 = 561.64 : x
  2. Step 2: Convert to fraction form
    821.38/1,229.64 = 561.64/x
  3. Step 3: Cross multiply
    821.38x = 1,229.64 × 561.64
  4. Step 4: Simplify right side
    821.38x = 690,615.01
  5. Step 5: Solve for x
    x = 690,615.01/821.38
  6. Step 6: Final answer
    x = 840.80

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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.