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Finding the Fourth Proportional to 121.05, 167.10 and 81.78

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Solution

The fourth proportional to 121.05, 167.10 and 81.78 is: 112.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.05 : 167.10 = 81.78 : x
  2. Step 2: Convert to fraction form
    121.05/167.10 = 81.78/x
  3. Step 3: Cross multiply
    121.05x = 167.10 × 81.78
  4. Step 4: Simplify right side
    121.05x = 13,665.44
  5. Step 5: Solve for x
    x = 13,665.44/121.05
  6. Step 6: Final answer
    x = 112.89

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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.