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Finding the Fourth Proportional to 138.26, 206.87 and 128.03

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Solution

The fourth proportional to 138.26, 206.87 and 128.03 is: 191.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.26 : 206.87 = 128.03 : x
  2. Step 2: Convert to fraction form
    138.26/206.87 = 128.03/x
  3. Step 3: Cross multiply
    138.26x = 206.87 × 128.03
  4. Step 4: Simplify right side
    138.26x = 26,485.57
  5. Step 5: Solve for x
    x = 26,485.57/138.26
  6. Step 6: Final answer
    x = 191.57

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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.