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Finding the Fourth Proportional to 321.48, 481.99 and 138.78

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Solution

The fourth proportional to 321.48, 481.99 and 138.78 is: 208.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    321.48 : 481.99 = 138.78 : x
  2. Step 2: Convert to fraction form
    321.48/481.99 = 138.78/x
  3. Step 3: Cross multiply
    321.48x = 481.99 × 138.78
  4. Step 4: Simplify right side
    321.48x = 66,890.57
  5. Step 5: Solve for x
    x = 66,890.57/321.48
  6. Step 6: Final answer
    x = 208.07

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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.