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Finding the Fourth Proportional to 138.65, 191.32 and 81.88

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Solution

The fourth proportional to 138.65, 191.32 and 81.88 is: 112.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.65 : 191.32 = 81.88 : x
  2. Step 2: Convert to fraction form
    138.65/191.32 = 81.88/x
  3. Step 3: Cross multiply
    138.65x = 191.32 × 81.88
  4. Step 4: Simplify right side
    138.65x = 15,664.33
  5. Step 5: Solve for x
    x = 15,664.33/138.65
  6. Step 6: Final answer
    x = 112.98

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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.