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Finding the Fourth Proportional to 1,311, 1,809.22 and 721.48

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Solution

The fourth proportional to 1,311, 1,809.22 and 721.48 is: 995.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311 : 1,809.22 = 721.48 : x
  2. Step 2: Convert to fraction form
    1,311/1,809.22 = 721.48/x
  3. Step 3: Cross multiply
    1,311x = 1,809.22 × 721.48
  4. Step 4: Simplify right side
    1,311x = 1,305,316.05
  5. Step 5: Solve for x
    x = 1,305,316.05/1,311
  6. Step 6: Final answer
    x = 995.66

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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.