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Finding the Fourth Proportional to 138.72, 207.24 and 121.44

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Solution

The fourth proportional to 138.72, 207.24 and 121.44 is: 181.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.72 : 207.24 = 121.44 : x
  2. Step 2: Convert to fraction form
    138.72/207.24 = 121.44/x
  3. Step 3: Cross multiply
    138.72x = 207.24 × 121.44
  4. Step 4: Simplify right side
    138.72x = 25,167.23
  5. Step 5: Solve for x
    x = 25,167.23/138.72
  6. Step 6: Final answer
    x = 181.42

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.