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Finding the Fourth Proportional to 821.46, 1,230.19 and 431.79

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Solution

The fourth proportional to 821.46, 1,230.19 and 431.79 is: 646.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.46 : 1,230.19 = 431.79 : x
  2. Step 2: Convert to fraction form
    821.46/1,230.19 = 431.79/x
  3. Step 3: Cross multiply
    821.46x = 1,230.19 × 431.79
  4. Step 4: Simplify right side
    821.46x = 531,187.40
  5. Step 5: Solve for x
    x = 531,187.40/821.46
  6. Step 6: Final answer
    x = 646.64

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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.