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Finding the Fourth Proportional to 207.20, 310.79 and 77.21

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Solution

The fourth proportional to 207.20, 310.79 and 77.21 is: 115.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.20 : 310.79 = 77.21 : x
  2. Step 2: Convert to fraction form
    207.20/310.79 = 77.21/x
  3. Step 3: Cross multiply
    207.20x = 310.79 × 77.21
  4. Step 4: Simplify right side
    207.20x = 23,996.17
  5. Step 5: Solve for x
    x = 23,996.17/207.20
  6. Step 6: Final answer
    x = 115.81

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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.