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Finding the Fourth Proportional to 821.14, 1,231.07 and 431.19

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Solution

The fourth proportional to 821.14, 1,231.07 and 431.19 is: 646.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.14 : 1,231.07 = 431.19 : x
  2. Step 2: Convert to fraction form
    821.14/1,231.07 = 431.19/x
  3. Step 3: Cross multiply
    821.14x = 1,231.07 × 431.19
  4. Step 4: Simplify right side
    821.14x = 530,822.92
  5. Step 5: Solve for x
    x = 530,822.92/821.14
  6. Step 6: Final answer
    x = 646.45

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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.