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Finding the Fourth Proportional to 138.90, 191.69 and 83.66

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Solution

The fourth proportional to 138.90, 191.69 and 83.66 is: 115.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.90 : 191.69 = 83.66 : x
  2. Step 2: Convert to fraction form
    138.90/191.69 = 83.66/x
  3. Step 3: Cross multiply
    138.90x = 191.69 × 83.66
  4. Step 4: Simplify right side
    138.90x = 16,036.79
  5. Step 5: Solve for x
    x = 16,036.79/138.90
  6. Step 6: Final answer
    x = 115.46

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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.