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Finding the Fourth Proportional to 781.11, 1,172.12 and 720.97

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Solution

The fourth proportional to 781.11, 1,172.12 and 720.97 is: 1,081.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.11 : 1,172.12 = 720.97 : x
  2. Step 2: Convert to fraction form
    781.11/1,172.12 = 720.97/x
  3. Step 3: Cross multiply
    781.11x = 1,172.12 × 720.97
  4. Step 4: Simplify right side
    781.11x = 845,063.36
  5. Step 5: Solve for x
    x = 845,063.36/781.11
  6. Step 6: Final answer
    x = 1,081.87

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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.