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Finding the Fourth Proportional to 1,311.29, 1,809.63 and 721.81

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Solution

The fourth proportional to 1,311.29, 1,809.63 and 721.81 is: 996.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.29 : 1,809.63 = 721.81 : x
  2. Step 2: Convert to fraction form
    1,311.29/1,809.63 = 721.81/x
  3. Step 3: Cross multiply
    1,311.29x = 1,809.63 × 721.81
  4. Step 4: Simplify right side
    1,311.29x = 1,306,196.37
  5. Step 5: Solve for x
    x = 1,306,196.37/1,311.29
  6. Step 6: Final answer
    x = 996.12

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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.