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Finding the Fourth Proportional to 138.78, 191.60 and 83.54

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Solution

The fourth proportional to 138.78, 191.60 and 83.54 is: 115.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 191.60 = 83.54 : x
  2. Step 2: Convert to fraction form
    138.78/191.60 = 83.54/x
  3. Step 3: Cross multiply
    138.78x = 191.60 × 83.54
  4. Step 4: Simplify right side
    138.78x = 16,004.89
  5. Step 5: Solve for x
    x = 16,004.89/138.78
  6. Step 6: Final answer
    x = 115.33

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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.