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Finding the Fourth Proportional to 143.80, 198.45 and 78.31

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Solution

The fourth proportional to 143.80, 198.45 and 78.31 is: 108.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.80 : 198.45 = 78.31 : x
  2. Step 2: Convert to fraction form
    143.80/198.45 = 78.31/x
  3. Step 3: Cross multiply
    143.80x = 198.45 × 78.31
  4. Step 4: Simplify right side
    143.80x = 15,540.62
  5. Step 5: Solve for x
    x = 15,540.62/143.80
  6. Step 6: Final answer
    x = 108.07

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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.