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Finding the Fourth Proportional to 138.64, 207.96 and 77.92

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Solution

The fourth proportional to 138.64, 207.96 and 77.92 is: 116.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.64 : 207.96 = 77.92 : x
  2. Step 2: Convert to fraction form
    138.64/207.96 = 77.92/x
  3. Step 3: Cross multiply
    138.64x = 207.96 × 77.92
  4. Step 4: Simplify right side
    138.64x = 16,204.24
  5. Step 5: Solve for x
    x = 16,204.24/138.64
  6. Step 6: Final answer
    x = 116.88

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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.