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Finding the Fourth Proportional to 138.06, 207 and 115.20

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Solution

The fourth proportional to 138.06, 207 and 115.20 is: 172.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.06 : 207 = 115.20 : x
  2. Step 2: Convert to fraction form
    138.06/207 = 115.20/x
  3. Step 3: Cross multiply
    138.06x = 207 × 115.20
  4. Step 4: Simplify right side
    138.06x = 23,846.40
  5. Step 5: Solve for x
    x = 23,846.40/138.06
  6. Step 6: Final answer
    x = 172.72

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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.