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Finding the Fourth Proportional to 138.82, 207.78 and 121

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Solution

The fourth proportional to 138.82, 207.78 and 121 is: 181.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.82 : 207.78 = 121 : x
  2. Step 2: Convert to fraction form
    138.82/207.78 = 121/x
  3. Step 3: Cross multiply
    138.82x = 207.78 × 121
  4. Step 4: Simplify right side
    138.82x = 25,141.38
  5. Step 5: Solve for x
    x = 25,141.38/138.82
  6. Step 6: Final answer
    x = 181.11

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.