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Finding the Fourth Proportional to 1,387.68, 2,079.90 and 1,078.61

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Solution

The fourth proportional to 1,387.68, 2,079.90 and 1,078.61 is: 1,616.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.68 : 2,079.90 = 1,078.61 : x
  2. Step 2: Convert to fraction form
    1,387.68/2,079.90 = 1,078.61/x
  3. Step 3: Cross multiply
    1,387.68x = 2,079.90 × 1,078.61
  4. Step 4: Simplify right side
    1,387.68x = 2,243,390.54
  5. Step 5: Solve for x
    x = 2,243,390.54/1,387.68
  6. Step 6: Final answer
    x = 1,616.65

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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.