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Finding the Fourth Proportional to 989.57, 1,367.21 and 979.85

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Solution

The fourth proportional to 989.57, 1,367.21 and 979.85 is: 1,353.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.57 : 1,367.21 = 979.85 : x
  2. Step 2: Convert to fraction form
    989.57/1,367.21 = 979.85/x
  3. Step 3: Cross multiply
    989.57x = 1,367.21 × 979.85
  4. Step 4: Simplify right side
    989.57x = 1,339,660.72
  5. Step 5: Solve for x
    x = 1,339,660.72/989.57
  6. Step 6: Final answer
    x = 1,353.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.