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Finding the Fourth Proportional to 1,379.30, 1,903 and 789.72

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Solution

The fourth proportional to 1,379.30, 1,903 and 789.72 is: 1,089.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,379.30 : 1,903 = 789.72 : x
  2. Step 2: Convert to fraction form
    1,379.30/1,903 = 789.72/x
  3. Step 3: Cross multiply
    1,379.30x = 1,903 × 789.72
  4. Step 4: Simplify right side
    1,379.30x = 1,502,837.16
  5. Step 5: Solve for x
    x = 1,502,837.16/1,379.30
  6. Step 6: Final answer
    x = 1,089.57

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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.