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Finding the Fourth Proportional to 138.67, 191.31 and 86.19

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Solution

The fourth proportional to 138.67, 191.31 and 86.19 is: 118.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.67 : 191.31 = 86.19 : x
  2. Step 2: Convert to fraction form
    138.67/191.31 = 86.19/x
  3. Step 3: Cross multiply
    138.67x = 191.31 × 86.19
  4. Step 4: Simplify right side
    138.67x = 16,489.70
  5. Step 5: Solve for x
    x = 16,489.70/138.67
  6. Step 6: Final answer
    x = 118.92

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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.