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Finding the Fourth Proportional to 781.31, 1,172.13 and 261.29

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Solution

The fourth proportional to 781.31, 1,172.13 and 261.29 is: 391.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.31 : 1,172.13 = 261.29 : x
  2. Step 2: Convert to fraction form
    781.31/1,172.13 = 261.29/x
  3. Step 3: Cross multiply
    781.31x = 1,172.13 × 261.29
  4. Step 4: Simplify right side
    781.31x = 306,265.85
  5. Step 5: Solve for x
    x = 306,265.85/781.31
  6. Step 6: Final answer
    x = 391.99

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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.