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Finding the Fourth Proportional to 321.20, 481.72 and 128.80

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Solution

The fourth proportional to 321.20, 481.72 and 128.80 is: 193.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    321.20 : 481.72 = 128.80 : x
  2. Step 2: Convert to fraction form
    321.20/481.72 = 128.80/x
  3. Step 3: Cross multiply
    321.20x = 481.72 × 128.80
  4. Step 4: Simplify right side
    321.20x = 62,045.54
  5. Step 5: Solve for x
    x = 62,045.54/321.20
  6. Step 6: Final answer
    x = 193.17

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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.