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Finding the Fourth Proportional to 138.81, 191 and 121.26

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Solution

The fourth proportional to 138.81, 191 and 121.26 is: 166.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.81 : 191 = 121.26 : x
  2. Step 2: Convert to fraction form
    138.81/191 = 121.26/x
  3. Step 3: Cross multiply
    138.81x = 191 × 121.26
  4. Step 4: Simplify right side
    138.81x = 23,160.66
  5. Step 5: Solve for x
    x = 23,160.66/138.81
  6. Step 6: Final answer
    x = 166.85

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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.