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Finding the Fourth Proportional to 138.98, 191.78 and 80.75

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Solution

The fourth proportional to 138.98, 191.78 and 80.75 is: 111.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.98 : 191.78 = 80.75 : x
  2. Step 2: Convert to fraction form
    138.98/191.78 = 80.75/x
  3. Step 3: Cross multiply
    138.98x = 191.78 × 80.75
  4. Step 4: Simplify right side
    138.98x = 15,486.24
  5. Step 5: Solve for x
    x = 15,486.24/138.98
  6. Step 6: Final answer
    x = 111.43

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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.