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Finding the Fourth Proportional to 821.80, 1,233.30 and 640.75

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Solution

The fourth proportional to 821.80, 1,233.30 and 640.75 is: 961.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.80 : 1,233.30 = 640.75 : x
  2. Step 2: Convert to fraction form
    821.80/1,233.30 = 640.75/x
  3. Step 3: Cross multiply
    821.80x = 1,233.30 × 640.75
  4. Step 4: Simplify right side
    821.80x = 790,236.98
  5. Step 5: Solve for x
    x = 790,236.98/821.80
  6. Step 6: Final answer
    x = 961.59

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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.