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Finding the Fourth Proportional to 1,387.32, 2,081.31 and 413.40

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Solution

The fourth proportional to 1,387.32, 2,081.31 and 413.40 is: 620.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.32 : 2,081.31 = 413.40 : x
  2. Step 2: Convert to fraction form
    1,387.32/2,081.31 = 413.40/x
  3. Step 3: Cross multiply
    1,387.32x = 2,081.31 × 413.40
  4. Step 4: Simplify right side
    1,387.32x = 860,413.55
  5. Step 5: Solve for x
    x = 860,413.55/1,387.32
  6. Step 6: Final answer
    x = 620.20

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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.