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Finding the Fourth Proportional to 138.20, 206.96 and 77.16

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Solution

The fourth proportional to 138.20, 206.96 and 77.16 is: 115.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.20 : 206.96 = 77.16 : x
  2. Step 2: Convert to fraction form
    138.20/206.96 = 77.16/x
  3. Step 3: Cross multiply
    138.20x = 206.96 × 77.16
  4. Step 4: Simplify right side
    138.20x = 15,969.03
  5. Step 5: Solve for x
    x = 15,969.03/138.20
  6. Step 6: Final answer
    x = 115.55

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.