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Finding the Fourth Proportional to 138.72, 191.52 and 121.56

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Solution

The fourth proportional to 138.72, 191.52 and 121.56 is: 167.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.72 : 191.52 = 121.56 : x
  2. Step 2: Convert to fraction form
    138.72/191.52 = 121.56/x
  3. Step 3: Cross multiply
    138.72x = 191.52 × 121.56
  4. Step 4: Simplify right side
    138.72x = 23,281.17
  5. Step 5: Solve for x
    x = 23,281.17/138.72
  6. Step 6: Final answer
    x = 167.83

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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.