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Finding the Fourth Proportional to 311.59, 467.21 and 128.78

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Solution

The fourth proportional to 311.59, 467.21 and 128.78 is: 193.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.59 : 467.21 = 128.78 : x
  2. Step 2: Convert to fraction form
    311.59/467.21 = 128.78/x
  3. Step 3: Cross multiply
    311.59x = 467.21 × 128.78
  4. Step 4: Simplify right side
    311.59x = 60,166.66
  5. Step 5: Solve for x
    x = 60,166.66/311.59
  6. Step 6: Final answer
    x = 193.10

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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.