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Finding the Fourth Proportional to 321.21, 481.91 and 138.51

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Solution

The fourth proportional to 321.21, 481.91 and 138.51 is: 207.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    321.21 : 481.91 = 138.51 : x
  2. Step 2: Convert to fraction form
    321.21/481.91 = 138.51/x
  3. Step 3: Cross multiply
    321.21x = 481.91 × 138.51
  4. Step 4: Simplify right side
    321.21x = 66,748.66
  5. Step 5: Solve for x
    x = 66,748.66/321.21
  6. Step 6: Final answer
    x = 207.80

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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.