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Finding the Fourth Proportional to 721.14, 1,081.56 and 345.90

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Solution

The fourth proportional to 721.14, 1,081.56 and 345.90 is: 518.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.14 : 1,081.56 = 345.90 : x
  2. Step 2: Convert to fraction form
    721.14/1,081.56 = 345.90/x
  3. Step 3: Cross multiply
    721.14x = 1,081.56 × 345.90
  4. Step 4: Simplify right side
    721.14x = 374,111.60
  5. Step 5: Solve for x
    x = 374,111.60/721.14
  6. Step 6: Final answer
    x = 518.78

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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.