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Finding the Fourth Proportional to 1,311.43, 1,809.20 and 813.07

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Solution

The fourth proportional to 1,311.43, 1,809.20 and 813.07 is: 1,121.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.43 : 1,809.20 = 813.07 : x
  2. Step 2: Convert to fraction form
    1,311.43/1,809.20 = 813.07/x
  3. Step 3: Cross multiply
    1,311.43x = 1,809.20 × 813.07
  4. Step 4: Simplify right side
    1,311.43x = 1,471,002.18
  5. Step 5: Solve for x
    x = 1,471,002.18/1,311.43
  6. Step 6: Final answer
    x = 1,121.68

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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.