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Finding the Fourth Proportional to 138.38, 190.71 and 128.61

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Solution

The fourth proportional to 138.38, 190.71 and 128.61 is: 177.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.38 : 190.71 = 128.61 : x
  2. Step 2: Convert to fraction form
    138.38/190.71 = 128.61/x
  3. Step 3: Cross multiply
    138.38x = 190.71 × 128.61
  4. Step 4: Simplify right side
    138.38x = 24,527.21
  5. Step 5: Solve for x
    x = 24,527.21/138.38
  6. Step 6: Final answer
    x = 177.25

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.