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Finding the Fourth Proportional to 138.78, 207.21 and 113.16

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Solution

The fourth proportional to 138.78, 207.21 and 113.16 is: 168.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 207.21 = 113.16 : x
  2. Step 2: Convert to fraction form
    138.78/207.21 = 113.16/x
  3. Step 3: Cross multiply
    138.78x = 207.21 × 113.16
  4. Step 4: Simplify right side
    138.78x = 23,447.88
  5. Step 5: Solve for x
    x = 23,447.88/138.78
  6. Step 6: Final answer
    x = 168.96

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.