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Finding the Fourth Proportional to 1,387.20, 2,081.20 and 413.32

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Solution

The fourth proportional to 1,387.20, 2,081.20 and 413.32 is: 620.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.20 : 2,081.20 = 413.32 : x
  2. Step 2: Convert to fraction form
    1,387.20/2,081.20 = 413.32/x
  3. Step 3: Cross multiply
    1,387.20x = 2,081.20 × 413.32
  4. Step 4: Simplify right side
    1,387.20x = 860,201.58
  5. Step 5: Solve for x
    x = 860,201.58/1,387.20
  6. Step 6: Final answer
    x = 620.10

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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.