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Finding the Fourth Proportional to 721.18, 1,080.72 and 428.82

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Solution

The fourth proportional to 721.18, 1,080.72 and 428.82 is: 642.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.18 : 1,080.72 = 428.82 : x
  2. Step 2: Convert to fraction form
    721.18/1,080.72 = 428.82/x
  3. Step 3: Cross multiply
    721.18x = 1,080.72 × 428.82
  4. Step 4: Simplify right side
    721.18x = 463,434.35
  5. Step 5: Solve for x
    x = 463,434.35/721.18
  6. Step 6: Final answer
    x = 642.61

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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.