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Finding the Fourth Proportional to 989.91, 1,481.90 and 642.24

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Solution

The fourth proportional to 989.91, 1,481.90 and 642.24 is: 961.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.91 : 1,481.90 = 642.24 : x
  2. Step 2: Convert to fraction form
    989.91/1,481.90 = 642.24/x
  3. Step 3: Cross multiply
    989.91x = 1,481.90 × 642.24
  4. Step 4: Simplify right side
    989.91x = 951,732.24
  5. Step 5: Solve for x
    x = 951,732.24/989.91
  6. Step 6: Final answer
    x = 961.43

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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.