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Finding the Fourth Proportional to 121.86, 168.05 and 80.42

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Solution

The fourth proportional to 121.86, 168.05 and 80.42 is: 110.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.86 : 168.05 = 80.42 : x
  2. Step 2: Convert to fraction form
    121.86/168.05 = 80.42/x
  3. Step 3: Cross multiply
    121.86x = 168.05 × 80.42
  4. Step 4: Simplify right side
    121.86x = 13,513.34
  5. Step 5: Solve for x
    x = 13,513.34/121.86
  6. Step 6: Final answer
    x = 110.89

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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.