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Finding the Fourth Proportional to 1,387.08, 1,914.20 and 789.56

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Solution

The fourth proportional to 1,387.08, 1,914.20 and 789.56 is: 1,089.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.08 : 1,914.20 = 789.56 : x
  2. Step 2: Convert to fraction form
    1,387.08/1,914.20 = 789.56/x
  3. Step 3: Cross multiply
    1,387.08x = 1,914.20 × 789.56
  4. Step 4: Simplify right side
    1,387.08x = 1,511,375.75
  5. Step 5: Solve for x
    x = 1,511,375.75/1,387.08
  6. Step 6: Final answer
    x = 1,089.61

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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.