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Finding the Fourth Proportional to 121.87, 168.21 and 92.80

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Solution

The fourth proportional to 121.87, 168.21 and 92.80 is: 128.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.87 : 168.21 = 92.80 : x
  2. Step 2: Convert to fraction form
    121.87/168.21 = 92.80/x
  3. Step 3: Cross multiply
    121.87x = 168.21 × 92.80
  4. Step 4: Simplify right side
    121.87x = 15,609.89
  5. Step 5: Solve for x
    x = 15,609.89/121.87
  6. Step 6: Final answer
    x = 128.09

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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.