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Finding the Fourth Proportional to 721.78, 1,083.20 and 259.56

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Solution

The fourth proportional to 721.78, 1,083.20 and 259.56 is: 389.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.78 : 1,083.20 = 259.56 : x
  2. Step 2: Convert to fraction form
    721.78/1,083.20 = 259.56/x
  3. Step 3: Cross multiply
    721.78x = 1,083.20 × 259.56
  4. Step 4: Simplify right side
    721.78x = 281,155.39
  5. Step 5: Solve for x
    x = 281,155.39/721.78
  6. Step 6: Final answer
    x = 389.53

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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.