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Finding the Fourth Proportional to 138.74, 208.16 and 80.96

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Solution

The fourth proportional to 138.74, 208.16 and 80.96 is: 121.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.74 : 208.16 = 80.96 : x
  2. Step 2: Convert to fraction form
    138.74/208.16 = 80.96/x
  3. Step 3: Cross multiply
    138.74x = 208.16 × 80.96
  4. Step 4: Simplify right side
    138.74x = 16,852.63
  5. Step 5: Solve for x
    x = 16,852.63/138.74
  6. Step 6: Final answer
    x = 121.47

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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.