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Finding the Fourth Proportional to 821.35, 1,231.19 and 431.79

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Solution

The fourth proportional to 821.35, 1,231.19 and 431.79 is: 647.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.35 : 1,231.19 = 431.79 : x
  2. Step 2: Convert to fraction form
    821.35/1,231.19 = 431.79/x
  3. Step 3: Cross multiply
    821.35x = 1,231.19 × 431.79
  4. Step 4: Simplify right side
    821.35x = 531,609.37
  5. Step 5: Solve for x
    x = 531,609.37/821.35
  6. Step 6: Final answer
    x = 647.24

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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.