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Finding the Fourth Proportional to 139.92, 193.20 and 121.68

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Solution

The fourth proportional to 139.92, 193.20 and 121.68 is: 168.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.92 : 193.20 = 121.68 : x
  2. Step 2: Convert to fraction form
    139.92/193.20 = 121.68/x
  3. Step 3: Cross multiply
    139.92x = 193.20 × 121.68
  4. Step 4: Simplify right side
    139.92x = 23,508.58
  5. Step 5: Solve for x
    x = 23,508.58/139.92
  6. Step 6: Final answer
    x = 168.01

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.