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Finding the Fourth Proportional to 321.12, 481.28 and 138.30

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Solution

The fourth proportional to 321.12, 481.28 and 138.30 is: 207.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    321.12 : 481.28 = 138.30 : x
  2. Step 2: Convert to fraction form
    321.12/481.28 = 138.30/x
  3. Step 3: Cross multiply
    321.12x = 481.28 × 138.30
  4. Step 4: Simplify right side
    321.12x = 66,560.33
  5. Step 5: Solve for x
    x = 66,560.33/321.12
  6. Step 6: Final answer
    x = 207.28

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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.