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Finding the Fourth Proportional to 81.82, 113.15 and 78.20

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Solution

The fourth proportional to 81.82, 113.15 and 78.20 is: 108.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.82 : 113.15 = 78.20 : x
  2. Step 2: Convert to fraction form
    81.82/113.15 = 78.20/x
  3. Step 3: Cross multiply
    81.82x = 113.15 × 78.20
  4. Step 4: Simplify right side
    81.82x = 8,848.33
  5. Step 5: Solve for x
    x = 8,848.33/81.82
  6. Step 6: Final answer
    x = 108.14

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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.