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Finding the Fourth Proportional to 138.80, 191.49 and 128.90

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Solution

The fourth proportional to 138.80, 191.49 and 128.90 is: 177.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.80 : 191.49 = 128.90 : x
  2. Step 2: Convert to fraction form
    138.80/191.49 = 128.90/x
  3. Step 3: Cross multiply
    138.80x = 191.49 × 128.90
  4. Step 4: Simplify right side
    138.80x = 24,683.06
  5. Step 5: Solve for x
    x = 24,683.06/138.80
  6. Step 6: Final answer
    x = 177.83

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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.