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Finding the Fourth Proportional to 1,387.80, 2,081.67 and 413.91

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Solution

The fourth proportional to 1,387.80, 2,081.67 and 413.91 is: 620.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.80 : 2,081.67 = 413.91 : x
  2. Step 2: Convert to fraction form
    1,387.80/2,081.67 = 413.91/x
  3. Step 3: Cross multiply
    1,387.80x = 2,081.67 × 413.91
  4. Step 4: Simplify right side
    1,387.80x = 861,624.03
  5. Step 5: Solve for x
    x = 861,624.03/1,387.80
  6. Step 6: Final answer
    x = 620.86

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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.