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Finding the Fourth Proportional to 138.35, 190.91 and 85.91

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Solution

The fourth proportional to 138.35, 190.91 and 85.91 is: 118.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.35 : 190.91 = 85.91 : x
  2. Step 2: Convert to fraction form
    138.35/190.91 = 85.91/x
  3. Step 3: Cross multiply
    138.35x = 190.91 × 85.91
  4. Step 4: Simplify right side
    138.35x = 16,400.34
  5. Step 5: Solve for x
    x = 16,400.34/138.35
  6. Step 6: Final answer
    x = 118.54

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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.