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Finding the Fourth Proportional to 138.78, 191.58 and 83.55

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Solution

The fourth proportional to 138.78, 191.58 and 83.55 is: 115.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 191.58 = 83.55 : x
  2. Step 2: Convert to fraction form
    138.78/191.58 = 83.55/x
  3. Step 3: Cross multiply
    138.78x = 191.58 × 83.55
  4. Step 4: Simplify right side
    138.78x = 16,006.51
  5. Step 5: Solve for x
    x = 16,006.51/138.78
  6. Step 6: Final answer
    x = 115.34

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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.