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Finding the Fourth Proportional to 139.29, 192.21 and 121.87

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Solution

The fourth proportional to 139.29, 192.21 and 121.87 is: 168.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.29 : 192.21 = 121.87 : x
  2. Step 2: Convert to fraction form
    139.29/192.21 = 121.87/x
  3. Step 3: Cross multiply
    139.29x = 192.21 × 121.87
  4. Step 4: Simplify right side
    139.29x = 23,424.42
  5. Step 5: Solve for x
    x = 23,424.42/139.29
  6. Step 6: Final answer
    x = 168.17

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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.