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Finding the Fourth Proportional to 821.77, 1,231.20 and 685.69

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Solution

The fourth proportional to 821.77, 1,231.20 and 685.69 is: 1,027.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.77 : 1,231.20 = 685.69 : x
  2. Step 2: Convert to fraction form
    821.77/1,231.20 = 685.69/x
  3. Step 3: Cross multiply
    821.77x = 1,231.20 × 685.69
  4. Step 4: Simplify right side
    821.77x = 844,221.53
  5. Step 5: Solve for x
    x = 844,221.53/821.77
  6. Step 6: Final answer
    x = 1,027.32

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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.