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Finding the Fourth Proportional to 1,311.23, 1,809.47 and 721.74

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Solution

The fourth proportional to 1,311.23, 1,809.47 and 721.74 is: 995.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.23 : 1,809.47 = 721.74 : x
  2. Step 2: Convert to fraction form
    1,311.23/1,809.47 = 721.74/x
  3. Step 3: Cross multiply
    1,311.23x = 1,809.47 × 721.74
  4. Step 4: Simplify right side
    1,311.23x = 1,305,963.27
  5. Step 5: Solve for x
    x = 1,305,963.27/1,311.23
  6. Step 6: Final answer
    x = 995.99

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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.