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Finding the Fourth Proportional to 821.38, 1,230.85 and 513.58

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Solution

The fourth proportional to 821.38, 1,230.85 and 513.58 is: 769.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.38 : 1,230.85 = 513.58 : x
  2. Step 2: Convert to fraction form
    821.38/1,230.85 = 513.58/x
  3. Step 3: Cross multiply
    821.38x = 1,230.85 × 513.58
  4. Step 4: Simplify right side
    821.38x = 632,139.94
  5. Step 5: Solve for x
    x = 632,139.94/821.38
  6. Step 6: Final answer
    x = 769.61

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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.