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Finding the Fourth Proportional to 138.68, 208.04 and 86.64

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Solution

The fourth proportional to 138.68, 208.04 and 86.64 is: 129.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.68 : 208.04 = 86.64 : x
  2. Step 2: Convert to fraction form
    138.68/208.04 = 86.64/x
  3. Step 3: Cross multiply
    138.68x = 208.04 × 86.64
  4. Step 4: Simplify right side
    138.68x = 18,023.37
  5. Step 5: Solve for x
    x = 18,023.37/138.68
  6. Step 6: Final answer
    x = 129.96

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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.