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Finding the Fourth Proportional to 138.50, 191.09 and 86.05

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Solution

The fourth proportional to 138.50, 191.09 and 86.05 is: 118.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.50 : 191.09 = 86.05 : x
  2. Step 2: Convert to fraction form
    138.50/191.09 = 86.05/x
  3. Step 3: Cross multiply
    138.50x = 191.09 × 86.05
  4. Step 4: Simplify right side
    138.50x = 16,443.29
  5. Step 5: Solve for x
    x = 16,443.29/138.50
  6. Step 6: Final answer
    x = 118.72

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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.