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Finding the Fourth Proportional to 138.63, 191.31 and 83.40

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Solution

The fourth proportional to 138.63, 191.31 and 83.40 is: 115.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.63 : 191.31 = 83.40 : x
  2. Step 2: Convert to fraction form
    138.63/191.31 = 83.40/x
  3. Step 3: Cross multiply
    138.63x = 191.31 × 83.40
  4. Step 4: Simplify right side
    138.63x = 15,955.25
  5. Step 5: Solve for x
    x = 15,955.25/138.63
  6. Step 6: Final answer
    x = 115.09

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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.