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Finding the Fourth Proportional to 721.20, 1,081.20 and 412.02

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Solution

The fourth proportional to 721.20, 1,081.20 and 412.02 is: 617.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.20 : 1,081.20 = 412.02 : x
  2. Step 2: Convert to fraction form
    721.20/1,081.20 = 412.02/x
  3. Step 3: Cross multiply
    721.20x = 1,081.20 × 412.02
  4. Step 4: Simplify right side
    721.20x = 445,476.02
  5. Step 5: Solve for x
    x = 445,476.02/721.20
  6. Step 6: Final answer
    x = 617.69

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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.