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Finding the Fourth Proportional to 721.85, 1,081.40 and 356.21

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Solution

The fourth proportional to 721.85, 1,081.40 and 356.21 is: 533.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.85 : 1,081.40 = 356.21 : x
  2. Step 2: Convert to fraction form
    721.85/1,081.40 = 356.21/x
  3. Step 3: Cross multiply
    721.85x = 1,081.40 × 356.21
  4. Step 4: Simplify right side
    721.85x = 385,198.31
  5. Step 5: Solve for x
    x = 385,198.31/721.85
  6. Step 6: Final answer
    x = 533.63

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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.