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Finding the Fourth Proportional to 821.25, 1,229.87 and 431.57

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Solution

The fourth proportional to 821.25, 1,229.87 and 431.57 is: 646.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.25 : 1,229.87 = 431.57 : x
  2. Step 2: Convert to fraction form
    821.25/1,229.87 = 431.57/x
  3. Step 3: Cross multiply
    821.25x = 1,229.87 × 431.57
  4. Step 4: Simplify right side
    821.25x = 530,779.15
  5. Step 5: Solve for x
    x = 530,779.15/821.25
  6. Step 6: Final answer
    x = 646.31

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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.