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Finding the Fourth Proportional to 138.45, 190.30 and 121.98

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Solution

The fourth proportional to 138.45, 190.30 and 121.98 is: 167.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.45 : 190.30 = 121.98 : x
  2. Step 2: Convert to fraction form
    138.45/190.30 = 121.98/x
  3. Step 3: Cross multiply
    138.45x = 190.30 × 121.98
  4. Step 4: Simplify right side
    138.45x = 23,212.49
  5. Step 5: Solve for x
    x = 23,212.49/138.45
  6. Step 6: Final answer
    x = 167.66

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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.