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Finding the Fourth Proportional to 143.78, 198.39 and 121.91

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Solution

The fourth proportional to 143.78, 198.39 and 121.91 is: 168.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.78 : 198.39 = 121.91 : x
  2. Step 2: Convert to fraction form
    143.78/198.39 = 121.91/x
  3. Step 3: Cross multiply
    143.78x = 198.39 × 121.91
  4. Step 4: Simplify right side
    143.78x = 24,184.73
  5. Step 5: Solve for x
    x = 24,184.73/143.78
  6. Step 6: Final answer
    x = 168.21

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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.