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Finding the Fourth Proportional to 143.78, 198.38 and 81.61

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Solution

The fourth proportional to 143.78, 198.38 and 81.61 is: 112.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.78 : 198.38 = 81.61 : x
  2. Step 2: Convert to fraction form
    143.78/198.38 = 81.61/x
  3. Step 3: Cross multiply
    143.78x = 198.38 × 81.61
  4. Step 4: Simplify right side
    143.78x = 16,189.50
  5. Step 5: Solve for x
    x = 16,189.50/143.78
  6. Step 6: Final answer
    x = 112.60

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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.