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Finding the Fourth Proportional to 781.97, 1,172.79 and 261.90

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Solution

The fourth proportional to 781.97, 1,172.79 and 261.90 is: 392.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.97 : 1,172.79 = 261.90 : x
  2. Step 2: Convert to fraction form
    781.97/1,172.79 = 261.90/x
  3. Step 3: Cross multiply
    781.97x = 1,172.79 × 261.90
  4. Step 4: Simplify right side
    781.97x = 307,153.70
  5. Step 5: Solve for x
    x = 307,153.70/781.97
  6. Step 6: Final answer
    x = 392.80

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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.