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Finding the Fourth Proportional to 138.54, 191.18 and 78.73

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Solution

The fourth proportional to 138.54, 191.18 and 78.73 is: 108.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.54 : 191.18 = 78.73 : x
  2. Step 2: Convert to fraction form
    138.54/191.18 = 78.73/x
  3. Step 3: Cross multiply
    138.54x = 191.18 × 78.73
  4. Step 4: Simplify right side
    138.54x = 15,051.15
  5. Step 5: Solve for x
    x = 15,051.15/138.54
  6. Step 6: Final answer
    x = 108.64

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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.