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Finding the Fourth Proportional to 1,311.06, 1,809.27 and 721.61

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Solution

The fourth proportional to 1,311.06, 1,809.27 and 721.61 is: 995.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.06 : 1,809.27 = 721.61 : x
  2. Step 2: Convert to fraction form
    1,311.06/1,809.27 = 721.61/x
  3. Step 3: Cross multiply
    1,311.06x = 1,809.27 × 721.61
  4. Step 4: Simplify right side
    1,311.06x = 1,305,578.28
  5. Step 5: Solve for x
    x = 1,305,578.28/1,311.06
  6. Step 6: Final answer
    x = 995.82

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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.