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Finding the Fourth Proportional to 138.42, 190.14 and 121.92

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Solution

The fourth proportional to 138.42, 190.14 and 121.92 is: 167.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.42 : 190.14 = 121.92 : x
  2. Step 2: Convert to fraction form
    138.42/190.14 = 121.92/x
  3. Step 3: Cross multiply
    138.42x = 190.14 × 121.92
  4. Step 4: Simplify right side
    138.42x = 23,181.87
  5. Step 5: Solve for x
    x = 23,181.87/138.42
  6. Step 6: Final answer
    x = 167.47

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.