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Finding the Fourth Proportional to 721.78, 1,080.73 and 413.20

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Solution

The fourth proportional to 721.78, 1,080.73 and 413.20 is: 618.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.78 : 1,080.73 = 413.20 : x
  2. Step 2: Convert to fraction form
    721.78/1,080.73 = 413.20/x
  3. Step 3: Cross multiply
    721.78x = 1,080.73 × 413.20
  4. Step 4: Simplify right side
    721.78x = 446,557.64
  5. Step 5: Solve for x
    x = 446,557.64/721.78
  6. Step 6: Final answer
    x = 618.69

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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.