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Finding the Fourth Proportional to 1,387.14, 1,913.94 and 789.66

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Solution

The fourth proportional to 1,387.14, 1,913.94 and 789.66 is: 1,089.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.14 : 1,913.94 = 789.66 : x
  2. Step 2: Convert to fraction form
    1,387.14/1,913.94 = 789.66/x
  3. Step 3: Cross multiply
    1,387.14x = 1,913.94 × 789.66
  4. Step 4: Simplify right side
    1,387.14x = 1,511,361.86
  5. Step 5: Solve for x
    x = 1,511,361.86/1,387.14
  6. Step 6: Final answer
    x = 1,089.55

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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.