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Finding the Fourth Proportional to 138.18, 190.61 and 85.70

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Solution

The fourth proportional to 138.18, 190.61 and 85.70 is: 118.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.18 : 190.61 = 85.70 : x
  2. Step 2: Convert to fraction form
    138.18/190.61 = 85.70/x
  3. Step 3: Cross multiply
    138.18x = 190.61 × 85.70
  4. Step 4: Simplify right side
    138.18x = 16,333.90
  5. Step 5: Solve for x
    x = 16,333.90/138.18
  6. Step 6: Final answer
    x = 118.21

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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.