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Finding the Fourth Proportional to 138.43, 191.03 and 78.61

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Solution

The fourth proportional to 138.43, 191.03 and 78.61 is: 108.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.43 : 191.03 = 78.61 : x
  2. Step 2: Convert to fraction form
    138.43/191.03 = 78.61/x
  3. Step 3: Cross multiply
    138.43x = 191.03 × 78.61
  4. Step 4: Simplify right side
    138.43x = 15,015.52
  5. Step 5: Solve for x
    x = 15,015.52/138.43
  6. Step 6: Final answer
    x = 108.47

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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.