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Finding the Fourth Proportional to 138.53, 191.15 and 86.75

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Solution

The fourth proportional to 138.53, 191.15 and 86.75 is: 119.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.53 : 191.15 = 86.75 : x
  2. Step 2: Convert to fraction form
    138.53/191.15 = 86.75/x
  3. Step 3: Cross multiply
    138.53x = 191.15 × 86.75
  4. Step 4: Simplify right side
    138.53x = 16,581.83
  5. Step 5: Solve for x
    x = 16,581.83/138.53
  6. Step 6: Final answer
    x = 119.70

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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.