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Finding the Fourth Proportional to 2,660.38, 3,990.47 and 811.40

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Solution

The fourth proportional to 2,660.38, 3,990.47 and 811.40 is: 1,217.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,660.38 : 3,990.47 = 811.40 : x
  2. Step 2: Convert to fraction form
    2,660.38/3,990.47 = 811.40/x
  3. Step 3: Cross multiply
    2,660.38x = 3,990.47 × 811.40
  4. Step 4: Simplify right side
    2,660.38x = 3,237,843.35
  5. Step 5: Solve for x
    x = 3,237,843.35/2,660.38
  6. Step 6: Final answer
    x = 1,217.06

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.