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Finding the Fourth Proportional to 812.05, 1,217.21 and 421.66

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Solution

The fourth proportional to 812.05, 1,217.21 and 421.66 is: 632.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.05 : 1,217.21 = 421.66 : x
  2. Step 2: Convert to fraction form
    812.05/1,217.21 = 421.66/x
  3. Step 3: Cross multiply
    812.05x = 1,217.21 × 421.66
  4. Step 4: Simplify right side
    812.05x = 513,246.66
  5. Step 5: Solve for x
    x = 513,246.66/812.05
  6. Step 6: Final answer
    x = 632.04

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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.