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Finding the Fourth Proportional to 311.85, 467.78 and 129.20

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Solution

The fourth proportional to 311.85, 467.78 and 129.20 is: 193.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.85 : 467.78 = 129.20 : x
  2. Step 2: Convert to fraction form
    311.85/467.78 = 129.20/x
  3. Step 3: Cross multiply
    311.85x = 467.78 × 129.20
  4. Step 4: Simplify right side
    311.85x = 60,434.19
  5. Step 5: Solve for x
    x = 60,434.19/311.85
  6. Step 6: Final answer
    x = 193.79

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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.