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Finding the Fourth Proportional to 680.89, 1,020.62 and 420.21

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Solution

The fourth proportional to 680.89, 1,020.62 and 420.21 is: 629.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.89 : 1,020.62 = 420.21 : x
  2. Step 2: Convert to fraction form
    680.89/1,020.62 = 420.21/x
  3. Step 3: Cross multiply
    680.89x = 1,020.62 × 420.21
  4. Step 4: Simplify right side
    680.89x = 428,874.73
  5. Step 5: Solve for x
    x = 428,874.73/680.89
  6. Step 6: Final answer
    x = 629.87

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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.