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Finding the Fourth Proportional to 128.15, 191.21 and 120.41

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Solution

The fourth proportional to 128.15, 191.21 and 120.41 is: 179.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.15 : 191.21 = 120.41 : x
  2. Step 2: Convert to fraction form
    128.15/191.21 = 120.41/x
  3. Step 3: Cross multiply
    128.15x = 191.21 × 120.41
  4. Step 4: Simplify right side
    128.15x = 23,022.94
  5. Step 5: Solve for x
    x = 23,022.94/128.15
  6. Step 6: Final answer
    x = 179.66

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.