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Finding the Fourth Proportional to 172.20, 258.11 and 138.02

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Solution

The fourth proportional to 172.20, 258.11 and 138.02 is: 206.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.20 : 258.11 = 138.02 : x
  2. Step 2: Convert to fraction form
    172.20/258.11 = 138.02/x
  3. Step 3: Cross multiply
    172.20x = 258.11 × 138.02
  4. Step 4: Simplify right side
    172.20x = 35,624.30
  5. Step 5: Solve for x
    x = 35,624.30/172.20
  6. Step 6: Final answer
    x = 206.88

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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.