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Finding the Fourth Proportional to 121.20, 168.42 and 120.72

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Solution

The fourth proportional to 121.20, 168.42 and 120.72 is: 167.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.20 : 168.42 = 120.72 : x
  2. Step 2: Convert to fraction form
    121.20/168.42 = 120.72/x
  3. Step 3: Cross multiply
    121.20x = 168.42 × 120.72
  4. Step 4: Simplify right side
    121.20x = 20,331.66
  5. Step 5: Solve for x
    x = 20,331.66/121.20
  6. Step 6: Final answer
    x = 167.75

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.