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Finding the Fourth Proportional to 138.56, 191.18 and 86.11

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Solution

The fourth proportional to 138.56, 191.18 and 86.11 is: 118.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.56 : 191.18 = 86.11 : x
  2. Step 2: Convert to fraction form
    138.56/191.18 = 86.11/x
  3. Step 3: Cross multiply
    138.56x = 191.18 × 86.11
  4. Step 4: Simplify right side
    138.56x = 16,462.25
  5. Step 5: Solve for x
    x = 16,462.25/138.56
  6. Step 6: Final answer
    x = 118.81

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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.