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Finding the Fourth Proportional to 121.90, 168.10 and 86.92

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Solution

The fourth proportional to 121.90, 168.10 and 86.92 is: 119.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.90 : 168.10 = 86.92 : x
  2. Step 2: Convert to fraction form
    121.90/168.10 = 86.92/x
  3. Step 3: Cross multiply
    121.90x = 168.10 × 86.92
  4. Step 4: Simplify right side
    121.90x = 14,611.24
  5. Step 5: Solve for x
    x = 14,611.24/121.90
  6. Step 6: Final answer
    x = 119.87

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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.