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Finding the Fourth Proportional to 138.64, 208.42 and 128.62

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Solution

The fourth proportional to 138.64, 208.42 and 128.62 is: 193.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.64 : 208.42 = 128.62 : x
  2. Step 2: Convert to fraction form
    138.64/208.42 = 128.62/x
  3. Step 3: Cross multiply
    138.64x = 208.42 × 128.62
  4. Step 4: Simplify right side
    138.64x = 26,806.98
  5. Step 5: Solve for x
    x = 26,806.98/138.64
  6. Step 6: Final answer
    x = 193.36

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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.