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Finding the Fourth Proportional to 138.87, 191.64 and 80.65

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Solution

The fourth proportional to 138.87, 191.64 and 80.65 is: 111.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.87 : 191.64 = 80.65 : x
  2. Step 2: Convert to fraction form
    138.87/191.64 = 80.65/x
  3. Step 3: Cross multiply
    138.87x = 191.64 × 80.65
  4. Step 4: Simplify right side
    138.87x = 15,455.34
  5. Step 5: Solve for x
    x = 15,455.34/138.87
  6. Step 6: Final answer
    x = 111.30

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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.