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Finding the Fourth Proportional to 729.72, 1,011.20 and 720.81

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Solution

The fourth proportional to 729.72, 1,011.20 and 720.81 is: 998.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    729.72 : 1,011.20 = 720.81 : x
  2. Step 2: Convert to fraction form
    729.72/1,011.20 = 720.81/x
  3. Step 3: Cross multiply
    729.72x = 1,011.20 × 720.81
  4. Step 4: Simplify right side
    729.72x = 728,879.47
  5. Step 5: Solve for x
    x = 728,879.47/729.72
  6. Step 6: Final answer
    x = 998.85

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.