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Finding the Fourth Proportional to 979.20, 1,469.70 and 809.70

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Solution

The fourth proportional to 979.20, 1,469.70 and 809.70 is: 1,215.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    979.20 : 1,469.70 = 809.70 : x
  2. Step 2: Convert to fraction form
    979.20/1,469.70 = 809.70/x
  3. Step 3: Cross multiply
    979.20x = 1,469.70 × 809.70
  4. Step 4: Simplify right side
    979.20x = 1,190,016.09
  5. Step 5: Solve for x
    x = 1,190,016.09/979.20
  6. Step 6: Final answer
    x = 1,215.29

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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.